fix(useErrorHandler): use unknown instead of Error (#89)

* fix(useErrorHandler): use unknown instead of Error type

* make the return type explicit
* treat null and undefined as no error

* docs(useErrorHandler): use unknown instead of error

Closes #83

README.md

@@ -289,7 +289,7 @@ See the recovery examples above.
 This is called when the `resetKeys` are changed (triggering a reset of the
 `ErrorBoundary`). It's called with the `prevResetKeys` and the `resetKeys`.
 
-### `useErrorHandler(error?: Error)`
+### `useErrorHandler(error?: unknown)`
 
 React's error boundaries feature is limited in that the boundaries can only
 handle errors thrown during React's lifecycles. To quote

src/index.tsx

@@ -165,12 +165,10 @@ function withErrorBoundary<P>(
   return Wrapped
 }
 
-function useErrorHandler<P = Error>(
-  givenError?: P | null | undefined,
-): React.Dispatch<React.SetStateAction<P | null>> {
-  const [error, setError] = React.useState<P | null>(null)
-  if (givenError) throw givenError
-  if (error) throw error
+function useErrorHandler(givenError?: unknown): (error: unknown) => void {
+  const [error, setError] = React.useState<unknown>(null)
+  if (givenError != null) throw givenError
+  if (error != null) throw error
   return setError
 }