diff --git a/packages/outdated-browser/src/__tests__/index.ts b/packages/outdated-browser/src/__tests__/index.ts
index 6e8fb2e4c..3fe7dedd7 100644
--- a/packages/outdated-browser/src/__tests__/index.ts
+++ b/packages/outdated-browser/src/__tests__/index.ts
@@ -7,7 +7,7 @@ const localStorageMock = (() => {
 
   return {
     getItem(key: string): unknown {
-      return store?.[key] || null
+      return store[key] || null
     },
     setItem(key: string, value: unknown) {
       store[key] = value?.toString()
@@ -42,7 +42,10 @@ describe('@outdated-browser', () => {
     jest.restoreAllMocks()
     sessionStorage.clear()
     // Clear dom for next test
-    document.getElementsByTagName('html')[0].innerHTML = ''
+    const htmlDocument = document.getElementsByTagName('html')[0]
+    if (htmlDocument) {
+      htmlDocument.innerHTML = ''
+    }
     fakeUA = undefined
   })
 
diff --git a/packages/random-name/src/index.ts b/packages/random-name/src/index.ts
index 5f6e90fec..4e476c8fc 100644
--- a/packages/random-name/src/index.ts
+++ b/packages/random-name/src/index.ts
@@ -826,8 +826,8 @@ const NAMES = [
 
 const randomName = (prefix = '', separator = '-'): string => {
   const name = `${
-    ADJECTIVES[Math.floor(Math.random() * ADJECTIVES.length)]
-  }${separator}${NAMES[Math.floor(Math.random() * NAMES.length)]}`
+    ADJECTIVES[Math.floor(Math.random() * ADJECTIVES.length)] ?? ''
+  }${separator}${NAMES[Math.floor(Math.random() * NAMES.length)] ?? ''}`
 
   /* Steve Wozniak is not boring. This is part of the docker names spec. */
   if (name === `boring${separator}wozniak`) {
diff --git a/packages/use-dataloader/src/DataLoaderProvider.tsx b/packages/use-dataloader/src/DataLoaderProvider.tsx
index 4f97f818c..2aebf4630 100644
--- a/packages/use-dataloader/src/DataLoaderProvider.tsx
+++ b/packages/use-dataloader/src/DataLoaderProvider.tsx
@@ -76,7 +76,8 @@ const DataLoaderProvider = ({
   )
 
   const getRequest = useCallback(
-    (key: string) => requestsRef.current[computeKey(key)],
+    (key: string): DataLoader<unknown, unknown> | undefined =>
+      requestsRef.current[computeKey(key)],
     [computeKey],
   )
 
@@ -114,13 +115,11 @@ const DataLoaderProvider = ({
 
   const clearCachedData = useCallback(
     (key: string) => {
-      if (typeof key === 'string') {
-        if (requestsRef.current[computeKey(key)]) {
-          requestsRef.current[computeKey(key)].clearData()
-        }
+      if (key && typeof key === 'string') {
+        getRequest(key)?.clearData()
       } else throw new Error(KEY_IS_NOT_STRING_ERROR)
     },
-    [computeKey],
+    [getRequest],
   )
   const clearAllCachedData = useCallback(() => {
     Object.values(requestsRef.current).forEach(request => {
@@ -149,12 +148,12 @@ const DataLoaderProvider = ({
         return getRequest(key)?.getData()
       }
 
-      return Object.values(requestsRef.current).reduce(
+      return Object.values(requestsRef.current).reduce<CachedData>(
         (acc, request) => ({
           ...acc,
           [request.key]: request.getData(),
         }),
-        {} as CachedData,
+        {},
       )
     },
     [getRequest],
@@ -163,15 +162,15 @@ const DataLoaderProvider = ({
   const getReloads = useCallback(
     (key?: string) => {
       if (key) {
-        return getRequest(key) ? () => getRequest(key).load(true) : undefined
+        return getRequest(key) ? () => getRequest(key)?.load(true) : undefined
       }
 
-      return Object.entries(requestsRef.current).reduce(
+      return Object.entries(requestsRef.current).reduce<Reloads>(
         (acc, [requestKey, { load }]) => ({
           ...acc,
           [requestKey]: () => load(true),
         }),
-        {} as Reloads,
+        {},
       )
     },
     [getRequest],
diff --git a/packages/use-dataloader/src/__tests__/DataLoaderProvider.test.tsx b/packages/use-dataloader/src/__tests__/DataLoaderProvider.test.tsx
index 15013e06d..587663e6a 100644
--- a/packages/use-dataloader/src/__tests__/DataLoaderProvider.test.tsx
+++ b/packages/use-dataloader/src/__tests__/DataLoaderProvider.test.tsx
@@ -129,7 +129,7 @@ describe('DataLoaderProvider', () => {
     expect(result.current.getRequest(TEST_KEY)).toBeDefined()
     const unknownReload = result.current.getReloads('unknown')
     expect(unknownReload).toBeUndefined()
-    await reloads?.['test']()
+    await reloads['test']?.()
     expect(method).toBeCalledTimes(3)
     await result.current.reloadAll()
     expect(method).toBeCalledTimes(4)
diff --git a/packages/use-dataloader/src/__tests__/useDataLoader.test.tsx b/packages/use-dataloader/src/__tests__/useDataLoader.test.tsx
index ab2e6b35a..e13897d51 100644
--- a/packages/use-dataloader/src/__tests__/useDataLoader.test.tsx
+++ b/packages/use-dataloader/src/__tests__/useDataLoader.test.tsx
@@ -199,19 +199,19 @@ describe('useDataLoader', () => {
       },
     )
 
-    expect(result.current[0].data).toBe(undefined)
-    expect(result.current[0].isLoading).toBe(true)
-    expect(result.current[1].data).toBe(undefined)
-    expect(result.current[1].isIdle).toBe(true)
-    await waitFor(() => expect(result.current[0].isSuccess).toBe(true))
-    expect(result.current[0].data).toBe(true)
-
-    result.current[1].reload().catch(undefined)
-    await waitFor(() => expect(result.current[1].isLoading).toBe(true))
-    expect(result.current[1].data).toBe(undefined)
-
-    await waitFor(() => expect(result.current[1].isSuccess).toBe(true))
-    expect(result.current[1].data).toBe(true)
+    expect(result.current[0]?.data).toBe(undefined)
+    expect(result.current[0]?.isLoading).toBe(true)
+    expect(result.current[1]?.data).toBe(undefined)
+    expect(result.current[1]?.isIdle).toBe(true)
+    await waitFor(() => expect(result.current[0]?.isSuccess).toBe(true))
+    expect(result.current[0]?.data).toBe(true)
+
+    result.current[1]?.reload().catch(undefined)
+    await waitFor(() => expect(result.current[1]?.isLoading).toBe(true))
+    expect(result.current[1]?.data).toBe(undefined)
+
+    await waitFor(() => expect(result.current[1]?.isSuccess).toBe(true))
+    expect(result.current[1]?.data).toBe(true)
   })
 
   test('should render correctly with enabled true', async () => {
@@ -693,23 +693,23 @@ describe('useDataLoader', () => {
       },
     )
 
-    expect(result.current[0].data).toBe(undefined)
-    expect(result.current[0].isLoading).toBe(true)
-    expect(result.current[0].isIdle).toBe(false)
-    expect(result.current[0].isSuccess).toBe(false)
-    expect(result.current[1].data).toBe(undefined)
-    expect(result.current[1].isIdle).toBe(false)
-    expect(result.current[1].isSuccess).toBe(false)
-    expect(result.current[1].isLoading).toBe(true)
-    await waitFor(() => expect(result.current[0].isSuccess).toBe(true))
-    expect(result.current[0].data).toBe(true)
-
-    result.current[1].reload().catch(undefined)
-    await waitFor(() => expect(result.current[1].isLoading).toBe(true))
-    expect(result.current[1].data).toBe(true)
-
-    await waitFor(() => expect(result.current[1].isSuccess).toBe(true))
-    expect(result.current[1].isSuccess).toBe(true)
+    expect(result.current[0]?.data).toBe(undefined)
+    expect(result.current[0]?.isLoading).toBe(true)
+    expect(result.current[0]?.isIdle).toBe(false)
+    expect(result.current[0]?.isSuccess).toBe(false)
+    expect(result.current[1]?.data).toBe(undefined)
+    expect(result.current[1]?.isIdle).toBe(false)
+    expect(result.current[1]?.isSuccess).toBe(false)
+    expect(result.current[1]?.isLoading).toBe(true)
+    await waitFor(() => expect(result.current[0]?.isSuccess).toBe(true))
+    expect(result.current[0]?.data).toBe(true)
+
+    result.current[1]?.reload().catch(undefined)
+    await waitFor(() => expect(result.current[1]?.isLoading).toBe(true))
+    expect(result.current[1]?.data).toBe(true)
+
+    await waitFor(() => expect(result.current[1]?.isSuccess).toBe(true))
+    expect(result.current[1]?.isSuccess).toBe(true)
     expect(fakePromise).toBeCalledTimes(2)
   })
 
@@ -782,20 +782,20 @@ describe('useDataLoader', () => {
         wrapper,
       },
     )
-    expect(result.current[0].data).toBe(undefined)
-    expect(result.current[0].isLoading).toBe(true)
-    expect(result.current[0].previousData).toBe(undefined)
+    expect(result.current[0]?.data).toBe(undefined)
+    expect(result.current[0]?.isLoading).toBe(true)
+    expect(result.current[0]?.previousData).toBe(undefined)
     expect(testingProps.method).toBeCalledTimes(1)
-    await waitFor(() => expect(result.current[0].isSuccess).toBe(true))
+    await waitFor(() => expect(result.current[0]?.isSuccess).toBe(true))
     testingProps.config2.enabled = true
     rerender(testingProps)
     expect(testingProps.method).toBeCalledTimes(1)
-    expect(result.current[0].data).toBe(true)
-    expect(result.current[1].data).toBe(true)
-    expect(result.current[0].isLoading).toBe(false)
-    expect(result.current[1].isLoading).toBe(false)
-    expect(result.current[0].previousData).toBe(undefined)
-    expect(result.current[1].previousData).toBe(undefined)
+    expect(result.current[0]?.data).toBe(true)
+    expect(result.current[1]?.data).toBe(true)
+    expect(result.current[0]?.isLoading).toBe(false)
+    expect(result.current[1]?.isLoading).toBe(false)
+    expect(result.current[0]?.previousData).toBe(undefined)
+    expect(result.current[1]?.previousData).toBe(undefined)
   })
 
   test('should render correctly with dataLifetime dont prevent double call', async () => {
@@ -819,24 +819,24 @@ describe('useDataLoader', () => {
         wrapper,
       },
     )
-    expect(result.current[0].data).toBe(undefined)
-    expect(result.current[0].isLoading).toBe(true)
-    expect(result.current[0].previousData).toBe(undefined)
+    expect(result.current[0]?.data).toBe(undefined)
+    expect(result.current[0]?.isLoading).toBe(true)
+    expect(result.current[0]?.previousData).toBe(undefined)
     expect(testingProps.method).toBeCalledTimes(1)
-    await waitFor(() => expect(result.current[0].isSuccess).toBe(true))
+    await waitFor(() => expect(result.current[0]?.isSuccess).toBe(true))
     testingProps.config2.enabled = true
     rerender(testingProps)
-    await waitFor(() => expect(result.current[0].isLoading).toBe(true))
-    await waitFor(() => expect(result.current[1].isLoading).toBe(true))
+    await waitFor(() => expect(result.current[0]?.isLoading).toBe(true))
+    await waitFor(() => expect(result.current[1]?.isLoading).toBe(true))
     expect(testingProps.method).toBeCalledTimes(2)
-    expect(result.current[0].data).toBe(true)
-    expect(result.current[0].isLoading).toBe(true)
-    expect(result.current[0].previousData).toBe(undefined)
-    expect(result.current[1].data).toBe(true)
-    expect(result.current[1].isLoading).toBe(true)
-    expect(result.current[1].previousData).toBe(undefined)
-    await waitFor(() => expect(result.current[0].isSuccess).toBe(true))
-    await waitFor(() => expect(result.current[1].isSuccess).toBe(true))
+    expect(result.current[0]?.data).toBe(true)
+    expect(result.current[0]?.isLoading).toBe(true)
+    expect(result.current[0]?.previousData).toBe(undefined)
+    expect(result.current[1]?.data).toBe(true)
+    expect(result.current[1]?.isLoading).toBe(true)
+    expect(result.current[1]?.previousData).toBe(undefined)
+    await waitFor(() => expect(result.current[0]?.isSuccess).toBe(true))
+    await waitFor(() => expect(result.current[1]?.isSuccess).toBe(true))
   })
 })
 /* eslint-enable no-console */
diff --git a/packages/use-dataloader/src/dataloader.ts b/packages/use-dataloader/src/dataloader.ts
index 776ff9ea8..9a7bdeb49 100644
--- a/packages/use-dataloader/src/dataloader.ts
+++ b/packages/use-dataloader/src/dataloader.ts
@@ -31,7 +31,7 @@ class DataLoader<ResultType, ErrorType> {
 
   public data?: ResultType
 
-  public observers: Array<() => void> = []
+  public observers: (() => void)[] = []
 
   public timeout?: number
 
@@ -99,6 +99,8 @@ class DataLoader<ResultType, ErrorType> {
 
       const data = await this.method()
 
+      // This can be set to false with .cancel even while the launch is pending
+      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
       if (!this.isCancelled) {
         DataLoader.cachedData[this.key] = data
         this.status = StatusEnum.SUCCESS
diff --git a/packages/use-dataloader/src/helpers.ts b/packages/use-dataloader/src/helpers.ts
index 5c09dd793..1f5eb459a 100644
--- a/packages/use-dataloader/src/helpers.ts
+++ b/packages/use-dataloader/src/helpers.ts
@@ -17,4 +17,4 @@ export const marshalQueryKey = (queryKey: KeyType) =>
           return subKey?.toString()
         })
         .join('.')
-    : queryKey?.toString()
+    : queryKey.toString()
diff --git a/packages/use-dataloader/src/useDataLoader.ts b/packages/use-dataloader/src/useDataLoader.ts
index e0d8c7c33..3157845c7 100644
--- a/packages/use-dataloader/src/useDataLoader.ts
+++ b/packages/use-dataloader/src/useDataLoader.ts
@@ -118,7 +118,7 @@ function useDataLoader<ResultType = unknown, ErrorType = Error>(
   }, [needLoad, request])
 
   useEffect(() => {
-    let interval: NodeJS.Timer
+    let interval: NodeJS.Timer | undefined
 
     if (pollingInterval) {
       interval = setInterval(() => {
diff --git a/packages/use-gtm/src/__tests__/__snapshots__/index.tsx.snap b/packages/use-gtm/src/__tests__/__snapshots__/index.tsx.snap
index 17321feef..f6fa45e0a 100644
--- a/packages/use-gtm/src/__tests__/__snapshots__/index.tsx.snap
+++ b/packages/use-gtm/src/__tests__/__snapshots__/index.tsx.snap
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 exports[`GTM hook Provider should call onLoadError if script fail to load 1`] = `
-"<script src="https://www.googletagmanager.com/gtm.js?id=testId"></script><script>window.dataLayer = window.dataLayer || [];</script><script>(function(w,d,s,l,i){w[l]=w[l]||[];
+"<script>window.dataLayer = window.dataLayer || [];</script><script src="https://www.googletagmanager.com/gtm.js?id=testId"></script><script>(function(w,d,s,l,i){w[l]=w[l]||[];
     w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});
     var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';
     j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl+'';
@@ -16,7 +16,7 @@ exports[`GTM hook Provider should call onLoadError if script fail to load 1`] =
 `;
 
 exports[`GTM hook Provider should load env when environment auth is missing 1`] = `
-"<script src="https://www.googletagmanager.com/gtm.js?id=testId"></script><script>window.dataLayer = window.dataLayer || [];</script><script>(function(w,d,s,l,i){w[l]=w[l]||[];
+"<script>window.dataLayer = window.dataLayer || [];</script><script src="https://www.googletagmanager.com/gtm.js?id=testId"></script><script>(function(w,d,s,l,i){w[l]=w[l]||[];
     w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});
     var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';
     j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl+'';
@@ -31,7 +31,7 @@ exports[`GTM hook Provider should load env when environment auth is missing 1`]
 `;
 
 exports[`GTM hook Provider should load when id and environment is provided 1`] = `
-"<script src="https://www.googletagmanager.com/gtm.js?id=testId&amp;gtm_auth=gtm&amp;gtm_preview=world&amp;gtm_cookies_win=x"></script><script>window.dataLayer = window.dataLayer || [];</script><script>(function(w,d,s,l,i){w[l]=w[l]||[];
+"<script>window.dataLayer = window.dataLayer || [];</script><script src="https://www.googletagmanager.com/gtm.js?id=testId&amp;gtm_auth=gtm&amp;gtm_preview=world&amp;gtm_cookies_win=x"></script><script>(function(w,d,s,l,i){w[l]=w[l]||[];
     w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});
     var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';
     j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl+'&gtm_auth=gtm&gtm_preview=world&gtm_cookies_win=x';
@@ -46,7 +46,7 @@ exports[`GTM hook Provider should load when id and environment is provided 1`] =
 `;
 
 exports[`GTM hook Provider should load when id is provided 1`] = `
-"<script src="https://www.googletagmanager.com/gtm.js?id=testId"></script><script>window.dataLayer = window.dataLayer || [];</script><script>(function(w,d,s,l,i){w[l]=w[l]||[];
+"<script>window.dataLayer = window.dataLayer || [];</script><script src="https://www.googletagmanager.com/gtm.js?id=testId"></script><script>(function(w,d,s,l,i){w[l]=w[l]||[];
     w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});
     var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';
     j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl+'';
diff --git a/packages/use-gtm/src/__tests__/index.tsx b/packages/use-gtm/src/__tests__/index.tsx
index 095892e8f..f2f311ee1 100644
--- a/packages/use-gtm/src/__tests__/index.tsx
+++ b/packages/use-gtm/src/__tests__/index.tsx
@@ -54,7 +54,7 @@ describe('GTM hook', () => {
     try {
       renderHook(() => useGTM())
     } catch (error) {
-      expect((error as Error)?.message).toBe(
+      expect((error as Error).message).toBe(
         'useGTM must be used within a GTMProvider',
       )
     }
diff --git a/packages/use-gtm/src/scripts.ts b/packages/use-gtm/src/scripts.ts
index 76fb0e178..23d8c9151 100644
--- a/packages/use-gtm/src/scripts.ts
+++ b/packages/use-gtm/src/scripts.ts
@@ -4,7 +4,7 @@ export const DATALAYER_NAME = 'dataLayer'
 export const LOAD_ERROR_EVENT = 'gtm_loading_error'
 
 const flattenEnvironment = (environment?: GTMEnvironment) =>
-  environment && environment.auth
+  environment?.auth
     ? `&${Object.entries({ ...environment, cookies_win: 'x' })
         .filter(([, value]) => !!value)
         .map(([key, value]) => `gtm_${key}=${value}`, '')
diff --git a/packages/use-gtm/src/useGTM.tsx b/packages/use-gtm/src/useGTM.tsx
index da0f329d2..5ceeaa14f 100644
--- a/packages/use-gtm/src/useGTM.tsx
+++ b/packages/use-gtm/src/useGTM.tsx
@@ -16,7 +16,7 @@ declare global {
 }
 
 export const sendGTM = (data: DataLayerEvent) => {
-  window?.[DATALAYER_NAME]?.push(data)
+  window[DATALAYER_NAME]?.push(data)
 }
 
 const GTMContext = createContext<GTMContextInterface | undefined>(undefined)
@@ -56,9 +56,9 @@ function GTMProvider<T extends Events>({
         environment,
       )
 
-      document.head.insertBefore(dataLayerInit, document.head.childNodes[0])
-      document.head.insertBefore(script, document.head.childNodes[1])
-      document.body.insertBefore(noScript, document.body.childNodes[0])
+      document.head.prepend(script)
+      document.head.prepend(dataLayerInit)
+      document.body.prepend(noScript)
 
       if (onLoadError) document.addEventListener(LOAD_ERROR_EVENT, onLoadError)
 
diff --git a/packages/use-i18n/src/__tests__/usei18n.tsx b/packages/use-i18n/src/__tests__/usei18n.tsx
index 25e33b17a..245499a1b 100644
--- a/packages/use-i18n/src/__tests__/usei18n.tsx
+++ b/packages/use-i18n/src/__tests__/usei18n.tsx
@@ -53,6 +53,16 @@ const wrapper =
     )
 
 describe('i18n hook', () => {
+  beforeEach(() => {
+    jest.spyOn(window, 'navigator', 'get').mockImplementation(
+      () =>
+        ({
+          language: 'en-US',
+          languages: ['en-US', 'en'],
+        } as unknown as Navigator),
+    )
+  })
+
   afterEach(() => {
     localStorage.clear()
     mockdate.reset()
@@ -70,7 +80,7 @@ describe('i18n hook', () => {
         ),
       })
     } catch (error) {
-      expect((error as Error)?.message).toBe(
+      expect((error as Error).message).toBe(
         'useTranslation must be used within a I18nProvider',
       )
     }
@@ -89,7 +99,7 @@ describe('i18n hook', () => {
         ),
       })
     } catch (error) {
-      expect((error as Error)?.message).toBe(
+      expect((error as Error).message).toBe(
         'useI18n must be used within a I18nProvider',
       )
     }
@@ -228,33 +238,6 @@ describe('i18n hook', () => {
   })
 
   it('should set current locale from navigator languages', async () => {
-    jest.spyOn(window, 'navigator', 'get').mockImplementation(
-      () =>
-        ({
-          language: 'en-US',
-          languages: ['en-US', 'en'],
-        } as unknown as Navigator),
-    )
-    const { result } = renderHook(() => useI18n(), {
-      wrapper: wrapper({
-        defaultLocale: 'fr',
-        supportedLocales: ['en', 'fr', 'es'],
-      }),
-    })
-
-    await waitFor(() => {
-      expect(result.current.currentLocale).toEqual('en')
-    })
-  })
-
-  it('should set current locale from navigator language', async () => {
-    jest.spyOn(window, 'navigator', 'get').mockImplementation(
-      () =>
-        ({
-          language: 'en',
-          languages: undefined,
-        } as unknown as Navigator),
-    )
     const { result } = renderHook(() => useI18n(), {
       wrapper: wrapper({
         defaultLocale: 'fr',
diff --git a/packages/use-i18n/src/formatUnit.ts b/packages/use-i18n/src/formatUnit.ts
index e1c172ad2..05ea44bf9 100644
--- a/packages/use-i18n/src/formatUnit.ts
+++ b/packages/use-i18n/src/formatUnit.ts
@@ -14,7 +14,7 @@ const exponents = [
   { name: 'yotta', symbol: 'Y' },
 ]
 
-type Exponent = typeof exponents[number]
+type Exponent = (typeof exponents)[number]
 type ExponentName =
   | ''
   | 'kilo'
@@ -254,6 +254,6 @@ const formatUnit = (
   locale: string,
   number: number,
   { unit, ...options }: FormatUnitOptions,
-): string => supportedUnits?.[unit]?.(locale, number, options) ?? ''
+): string => supportedUnits[unit]?.(locale, number, options) ?? ''
 
 export default formatUnit
diff --git a/packages/use-i18n/src/formatters.ts b/packages/use-i18n/src/formatters.ts
index 1c48e8a4b..46ca4fd8e 100644
--- a/packages/use-i18n/src/formatters.ts
+++ b/packages/use-i18n/src/formatters.ts
@@ -41,6 +41,7 @@ function createFastMemoizeCache<V>(): Cache<string, V> {
   const store: Record<string, V> = {}
 
   return {
+    // @ts-expect-error waiting for https://github.com/formatjs/formatjs/pull/3964
     create() {
       return {
         get(key) {
diff --git a/packages/use-i18n/src/usei18n.tsx b/packages/use-i18n/src/usei18n.tsx
index 421176ae6..06d7e4797 100644
--- a/packages/use-i18n/src/usei18n.tsx
+++ b/packages/use-i18n/src/usei18n.tsx
@@ -38,7 +38,8 @@ const areNamespacesLoaded = (
   loadedNamespaces: string[] = [],
 ) => namespaces.every(n => loadedNamespaces.includes(n))
 
-const getLocaleFallback = (locale: string) => locale.split('-')[0].split('_')[0]
+const getLocaleFallback = (locale: string) =>
+  locale.split('-')[0]?.split('_')[0]
 
 const getCurrentLocale = ({
   defaultLocale,
@@ -49,13 +50,15 @@ const getCurrentLocale = ({
   supportedLocales: string[]
   localeItemStorage: string
 }): string => {
-  const languages = navigator.languages || [navigator.language]
+  const { languages } = navigator
   const browserLocales = [...new Set(languages.map(getLocaleFallback))]
   const localeStorage = localStorage.getItem(localeItemStorage)
 
   return (
     localeStorage ||
-    browserLocales.find(locale => supportedLocales.includes(locale)) ||
+    browserLocales.find(
+      locale => locale && supportedLocales.includes(locale),
+    ) ||
     defaultLocale
   )
 }
@@ -133,7 +136,7 @@ export function useTranslation<Locale extends BaseLocale = {}>(
   useEffect(() => {
     key
       .split(',')
-      .map(async (namespace: string) => loadTranslations?.(namespace, load))
+      .map(async (namespace: string) => loadTranslations(namespace, load))
   }, [loadTranslations, key, load])
 
   const isLoaded = useMemo(
@@ -158,13 +161,15 @@ type LoadTranslationsFn = ({
 }) => Promise<{ default: BaseLocale }>
 type LoadLocaleFn = (locale: string) => Promise<Locale>
 
+const initialDefaultTranslations = {}
+
 const I18nContextProvider = ({
   children,
   defaultLoad,
   loadDateLocale,
   defaultDateLocale,
   defaultLocale,
-  defaultTranslations = {},
+  defaultTranslations = initialDefaultTranslations,
   enableDefaultLocale = false,
   enableDebugKey = false,
   localeItemStorage = LOCALE_ITEM_STORAGE,
@@ -217,7 +222,7 @@ const I18nContextProvider = ({
 
       const trad: Record<string, string> = {
         ...result.defaultLocale.default,
-        ...result[currentLocale].default,
+        ...result[currentLocale]?.default,
       }
 
       // avoid a lot of render when async update
@@ -234,9 +239,7 @@ const I18nContextProvider = ({
           },
         }))
 
-        setNamespaces(prevState => [
-          ...new Set([...(prevState || []), namespace]),
-        ])
+        setNamespaces(prevState => [...new Set([...prevState, namespace])])
       })
 
       return namespace
diff --git a/packages/use-query-params/src/index.ts b/packages/use-query-params/src/index.ts
index 158dad95e..eb86fbc09 100644
--- a/packages/use-query-params/src/index.ts
+++ b/packages/use-query-params/src/index.ts
@@ -10,7 +10,7 @@ type Options = {
 type QueryParamValue = string | number | boolean | null | undefined
 
 type QueryParams = {
-  [key: string]: QueryParamValue | Array<QueryParamValue>
+  [key: string]: QueryParamValue | QueryParamValue[]
 }
 
 const useQueryParams = <T extends QueryParams>(): {
diff --git a/packages/use-segment/src/__tests__/index.tsx b/packages/use-segment/src/__tests__/index.tsx
index e14b1bd3b..9bccffd37 100644
--- a/packages/use-segment/src/__tests__/index.tsx
+++ b/packages/use-segment/src/__tests__/index.tsx
@@ -74,7 +74,7 @@ describe('segment hook', () => {
     try {
       renderHook(() => useSegment())
     } catch (error) {
-      expect((error as Error)?.message).toBe(
+      expect((error as Error).message).toBe(
         'useSegment must be used within a SegmentProvider',
       )
     }
diff --git a/packages/use-segment/src/useSegment.tsx b/packages/use-segment/src/useSegment.tsx
index d17edf46e..eb9b9d8ce 100644
--- a/packages/use-segment/src/useSegment.tsx
+++ b/packages/use-segment/src/useSegment.tsx
@@ -24,9 +24,11 @@ const SegmentContext = createContext<SegmentContextInterface | undefined>(
 )
 
 export function useSegment<T extends Events>(): SegmentContextInterface<T> {
-  // @ts-expect-error Here we force cast the generic onto the useContext because the context is a
-  // global variable and cannot be generic
-  const context = useContext<SegmentContextInterface<T>>(SegmentContext)
+  const context = useContext<SegmentContextInterface<T> | undefined>(
+    // @ts-expect-error Here we force cast the generic onto the useContext because the context is a
+    // global variable and cannot be generic
+    SegmentContext,
+  )
   if (context === undefined) {
     throw new Error('useSegment must be used within a SegmentProvider')
   }
diff --git a/packages/use-storage/src/index.ts b/packages/use-storage/src/index.ts
index 8c80748b4..4b001e802 100644
--- a/packages/use-storage/src/index.ts
+++ b/packages/use-storage/src/index.ts
@@ -18,9 +18,9 @@ declare global {
 
 const canUseDOM = !!(
   typeof window !== 'undefined' &&
-  typeof window?.document !== 'undefined' &&
-  typeof window?.localStorage !== 'undefined' &&
-  typeof window?.sessionStorage !== 'undefined'
+  typeof window.document !== 'undefined' &&
+  typeof window.localStorage !== 'undefined' &&
+  typeof window.sessionStorage !== 'undefined'
 )
 
 const subscribeStorage = (callback: () => void) => {
@@ -51,7 +51,7 @@ const useStorage = <T>(
   )
 
   const [localValue, setLocaleValue] = useState<string | null>(() =>
-    options?.initialValue ? JSON.stringify(options?.initialValue) : null,
+    options?.initialValue ? JSON.stringify(options.initialValue) : null,
   )
 
   const value = useSyncExternalStore(
diff --git a/packages/validate-icu-locales/src/index.ts b/packages/validate-icu-locales/src/index.ts
index 3455e5a65..a2901861b 100644
--- a/packages/validate-icu-locales/src/index.ts
+++ b/packages/validate-icu-locales/src/index.ts
@@ -27,12 +27,8 @@ const findICUErrors = (
   locales: { [key: string]: string },
   filePath: string,
 ): ErrorsICU => {
-  const keys = Object.keys(locales)
-
-  const errors = keys
-    .map(key => {
-      const value = locales[key]
-
+  const errors = Object.entries(locales)
+    .map(([key, value]) => {
       try {
         parse(value)
 
@@ -103,6 +99,11 @@ const readFiles = async (files: string[]): Promise<ErrorsICU> => {
   return errors
 }
 
+if (!pattern) {
+  error('Missing pattern: validate-icu-locales [PATTERN]')
+  process.exit(1)
+}
+
 const files = await globby(pattern)
 
 if (files.length === 0) {
diff --git a/tsconfig.json b/tsconfig.json
index d63483681..ac902a6f3 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -7,10 +7,7 @@
 
     "noEmit": true,
     "allowJs": true,
-    "jsx": "preserve",
-
-    // Should be removed once we clear all errors
-    "noUncheckedIndexedAccess": false
+    "jsx": "preserve"
   },
   "include": ["**/*.ts", "**/*.js", "**/.*.js", "**/*.tsx"],
   "exclude": [