diff --git a/core/package.json b/core/package.json
index 2f204067f..e531f2a7e 100644
--- a/core/package.json
+++ b/core/package.json
@@ -7,8 +7,8 @@
   "types": "lib/index.d.ts",
   "scripts": {
     "start": "npm run watch",
-    "build": "tsbb build --file-names src/bin/kkt.ts --file-names src/scripts/build.ts --file-names src/scripts/doc.ts --file-names src/scripts/start.ts --file-names src/scripts/testk.ts --no-esm",
-    "watch": "tsbb watch --file-names src/bin/kkt.ts --file-names src/scripts/build.ts --file-names src/scripts/doc.ts --file-names src/scripts/start.ts --file-names src/scripts/testk.ts --no-esm",
+    "build": "tsbb build src/*.ts --use-babel --no-esm",
+    "watch": "tsbb watch src/*.ts --use-babel --no-esm",
     "test": "tsbb test",
     "coverage": "tsbb test --coverage"
   },
diff --git a/core/src/global.d.ts b/core/src/global.d.ts
new file mode 100644
index 000000000..2805a4a37
--- /dev/null
+++ b/core/src/global.d.ts
@@ -0,0 +1,7 @@
+declare const require: {
+  (u: string): any;
+  cache: {
+    [key: string]: any;
+  };
+  resolve(path: string): string;
+};
diff --git a/core/src/overrides/checkRequired.ts b/core/src/overrides/checkRequired.ts
index 5c9bcade1..d435cb43d 100644
--- a/core/src/overrides/checkRequired.ts
+++ b/core/src/overrides/checkRequired.ts
@@ -10,7 +10,7 @@ import { OverridePaths } from './paths';
  */
 export function checkRequiredFiles(paths: OverridePaths, isNotCheckHTML: boolean) {
   const checkRequiredFilesPath = `${reactDevUtils}/checkRequiredFiles`;
-  require.cache[require.resolve(checkRequiredFilesPath)].exports = (files: fs.PathLike[]) => {
+  require.cache[require.resolve(checkRequiredFilesPath)].exports = (files: (fs.PathLike | undefined)[] = []) => {
     files = files
       .map((item) => {
         if (/(\.html)$/.test(item as string) && isNotCheckHTML) {
@@ -26,15 +26,17 @@ export function checkRequiredFiles(paths: OverridePaths, isNotCheckHTML: boolean
     try {
       files.forEach((filePath) => {
         currentFilePath = filePath;
-        fs.accessSync(filePath, fs.constants.F_OK);
+        filePath && fs.accessSync(filePath, fs.constants.F_OK);
       });
       return true;
     } catch (err) {
-      const dirName = path.dirname(currentFilePath);
-      const fileName = path.basename(currentFilePath);
-      console.log('\x1b[1;31m Could not find a required file. \x1b[0m');
-      console.log(`\x1b[1;31m   Name:  \x1b[0m ${fileName}`);
-      console.log(`\x1b[1;31m   Searched in: \x1b[0m \x1b[1;36m${dirName}\x1b[0m`);
+      if (currentFilePath) {
+        const dirName = path.dirname(currentFilePath);
+        const fileName = path.basename(currentFilePath);
+        console.log('\x1b[1;31m Could not find a required file. \x1b[0m');
+        console.log(`\x1b[1;31m   Name:  \x1b[0m ${fileName}`);
+        console.log(`\x1b[1;31m   Searched in: \x1b[0m \x1b[1;36m${dirName}\x1b[0m`);
+      }
       return false;
     }
   };
diff --git a/core/src/plugins/miniCssExtractPlugin.ts b/core/src/plugins/miniCssExtractPlugin.ts
index 7ea4b3918..f7c12dfac 100644
--- a/core/src/plugins/miniCssExtractPlugin.ts
+++ b/core/src/plugins/miniCssExtractPlugin.ts
@@ -23,7 +23,7 @@ export const miniCssExtractPlugin = (
   options: MiniCssExtractPlugin.PluginOptions = {},
 ) => {
   const regexp = /(MiniCssExtractPlugin)/;
-  conf.plugins = conf.plugins
+  conf.plugins = (conf.plugins || [])
     .map((item) => {
       if (item.constructor && item.constructor.name && regexp.test(item.constructor.name)) {
         return new MiniCssExtractPlugin({
diff --git a/core/src/plugins/staticDoc.ts b/core/src/plugins/staticDoc.ts
index ef0aad1e0..6085281b9 100644
--- a/core/src/plugins/staticDoc.ts
+++ b/core/src/plugins/staticDoc.ts
@@ -41,25 +41,25 @@ export function getDocsData(str: string = '', route = '/_doc'): DocsDataResult {
     result.dirPath = arr[0];
     result.route = arr[1] || route;
   }
-  if (!result.route.startsWith('/')) {
+  if (result.route && !result.route.startsWith('/')) {
     result.route = '/' + result.route;
   }
   // relative directory
   if (fs.existsSync(path.resolve(dirPath))) {
     result.docRoot = path.resolve(dirPath);
-    result.pkgPath = resolvePackagePath(process.cwd(), process.cwd());
-    const pkg = fs.readJSONSync(result.pkgPath);
+    result.pkgPath = resolvePackagePath(process.cwd(), process.cwd()) || '';
+    const pkg = fs.readJSONSync(result.pkgPath!);
     result.name = pkg.name;
     result.route = '/';
     return result;
   }
 
-  const [_, name] = dirPath.match(/^([a-zA-Z\-]+|@[a-zA-Z\-]+\/[a-zA-Z\-]+)\/?/i);
+  const [_, name] = dirPath.match(/^([a-zA-Z\-]+|@[a-zA-Z\-]+\/[a-zA-Z\-]+)\/?/i) || [];
   result.name = name;
-  result.pkgPath = resolvePackagePath(name, process.cwd());
-  result.root = path.dirname(result.pkgPath).replace(new RegExp(`${name.replace('/', path.sep)}$`, 'ig'), '');
+  result.pkgPath = resolvePackagePath(name, process.cwd()) || '';
+  result.root = path.dirname(result.pkgPath!).replace(new RegExp(`${name.replace('/', path.sep)}$`, 'ig'), '');
   const [repath] = str.replace(name, '').split(':');
-  result.docRoot = path.resolve(path.dirname(result.pkgPath) + repath);
+  result.docRoot = path.resolve(path.dirname(result.pkgPath!) + repath);
   return { ...result };
 }
 
@@ -78,7 +78,9 @@ export const staticDocSetupMiddlewares = (
     if (options.config?.output?.publicPath && typeof options.config.output.publicPath === 'string') {
       routePath = options.config.output.publicPath.replace(/\/+$/, '') + route;
     }
-    devServer.app.use(routePath, express.static(docRoot));
+    if (routePath && docRoot) {
+      devServer.app && devServer.app.use(routePath, express.static(docRoot));
+    }
   }
   return middlewares;
 };
diff --git a/core/src/scripts/build.ts b/core/src/scripts/build.ts
index b6b0a1287..4cf6d6e1b 100644
--- a/core/src/scripts/build.ts
+++ b/core/src/scripts/build.ts
@@ -50,7 +50,7 @@ export default async function build(argvs: BuildArgs) {
     // run original script
     await require(`${reactScripts}/scripts/build`);
   } catch (error) {
-    const message = error && error.message ? error.message : '';
+    const message = error && error instanceof Error && error.message ? error.message : '';
     console.log('\x1b[31;1m KKT:BUILD:ERROR: \x1b[0m\n', error);
     new Error(`KKT:BUILD:ERROR: \n ${message}`);
     process.exit(1);
diff --git a/core/src/scripts/doc.ts b/core/src/scripts/doc.ts
index 75d8d16b0..a9ed39750 100644
--- a/core/src/scripts/doc.ts
+++ b/core/src/scripts/doc.ts
@@ -18,12 +18,14 @@ export interface DocsArgs extends BuildArgs {
 export default async function docs(argv: DocsArgs) {
   try {
     const { route, docRoot, dirPath, ...other } = getDocsData(argv.path, '/');
-    app.use(route, express.static(docRoot), (req, res, next) => {
-      const content = fs.readFileSync(path.resolve(docRoot, './index.html'));
-      res.send(content.toString());
-      next();
-    });
-    const DEFAULT_PORT = parseInt(process.env.DOC_PORT, 10) || argv.port || 3002;
+    if (route && docRoot) {
+      app.use(route, express.static(docRoot), (req, res, next) => {
+        const content = fs.readFileSync(path.resolve(docRoot, './index.html'));
+        res.send(content.toString());
+        next();
+      });
+    }
+    const DEFAULT_PORT = (process.env.DOC_PORT && parseInt(process.env.DOC_PORT, 10)) || argv.port || 3002;
     const port = await choosePort(HOST, DEFAULT_PORT);
     app.listen(port, () => {
       const urls = prepareUrls(
@@ -38,7 +40,7 @@ export default async function docs(argv: DocsArgs) {
       console.log(`   On Your Network:  ${urls.localUrlForTerminal}`);
     });
   } catch (error) {
-    const message = error && error.message ? error.message : '';
+    const message = error && error instanceof Error && error.message ? error.message : '';
     console.log('\x1b[31;1m KKT:DOC:ERROR: \x1b[0m\n', error);
     new Error(`KKT:BUILD:ERROR: \n ${message}`);
     process.exit(1);
diff --git a/core/src/scripts/start.ts b/core/src/scripts/start.ts
index f09f86274..4faf1f8fd 100644
--- a/core/src/scripts/start.ts
+++ b/core/src/scripts/start.ts
@@ -108,7 +108,7 @@ export default async function start(argvs: StartArgs) {
         // Keep `evalSourceMapMiddleware`
         // middlewares before `redirectServedPath` otherwise will not have any effect
         // This lets us fetch source contents from webpack for the error overlay
-        devServer.app.use(evalSourceMapMiddleware(devServer));
+        devServer.app && devServer.app.use(evalSourceMapMiddleware(devServer));
         if (fs.existsSync(paths.proxySetup)) {
           // This registers user provided middleware for proxy reasons
           require(paths.proxySetup)(devServer.app);
@@ -119,14 +119,14 @@ export default async function start(argvs: StartArgs) {
         }
 
         // Redirect to `PUBLIC_URL` or `homepage` from `package.json` if url not match
-        devServer.app.use(redirectServedPath(paths.publicUrlOrPath));
+        devServer.app && devServer.app.use(redirectServedPath(paths.publicUrlOrPath));
 
         // This service worker file is effectively a 'no-op' that will reset any
         // previous service worker registered for the same host:port combination.
         // We do this in development to avoid hitting the production cache if
         // it used the same host and port.
         // https://github.com/facebook/create-react-app/issues/2272#issuecomment-302832432
-        devServer.app.use(noopServiceWorkerMiddleware(paths.publicUrlOrPath));
+        devServer.app && devServer.app.use(noopServiceWorkerMiddleware(paths.publicUrlOrPath));
         const mds = setupMiddlewares ? setupMiddlewares(middlewares, devServer) : middlewares;
         return staticDocSetupMiddlewares(mds, devServer, { ...argvs, paths, config: webpackConf });
       };
@@ -142,7 +142,7 @@ export default async function start(argvs: StartArgs) {
           console.log('❌ KKT:\x1b[31;1mERR\x1b[0m:', err);
           return;
         }
-        if (stats.hasErrors()) {
+        if (stats && stats.hasErrors()) {
           clearConsole();
           console.log(`❌ KKT:\x1b[31;1mERR\x1b[0m: \x1b[35;1m${today()}\x1b[0m\n`, stats.toString());
           return;
@@ -156,7 +156,7 @@ export default async function start(argvs: StartArgs) {
       require(`${reactScripts}/scripts/start`);
     }
   } catch (error) {
-    const message = error && error.message ? error.message : '';
+    const message = error && error instanceof Error && error.message ? error.message : '';
     console.log('\x1b[31;1m KKT:START:ERROR: \x1b[0m\n', error);
     new Error(`KKT:START:ERROR: \n ${message}`);
     process.exit(1);
diff --git a/core/src/scripts/testk.ts b/core/src/scripts/testk.ts
index 9ad8a82c8..31bdc7c4a 100644
--- a/core/src/scripts/testk.ts
+++ b/core/src/scripts/testk.ts
@@ -15,7 +15,7 @@ export default async function test(argvs: TestArgs) {
     // run original script
     require(`${reactScripts}/scripts/test`);
   } catch (error) {
-    const message = error && error.message ? error.message : '';
+    const message = error && error instanceof Error && error.message ? error.message : '';
     console.log('\x1b[31;1m KKT:TEST:ERROR: \x1b[0m\n', error);
     new Error(`KKT:TEST:ERROR: \n ${message}`);
     process.exit(1);
diff --git a/core/src/utils/loaderConf.ts b/core/src/utils/loaderConf.ts
index 371327ef7..e5f2e20db 100644
--- a/core/src/utils/loaderConf.ts
+++ b/core/src/utils/loaderConf.ts
@@ -95,7 +95,7 @@ export async function loaderConf(rcPath: string): Promise<KKTRC> {
     }
     return kktrc;
   } catch (error) {
-    const message = error && error.message ? error.message : '';
+    const message = error && error instanceof Error && error.message ? error.message : '';
     console.log('Invalid \x1b[31;1m .kktrc.js \x1b[0m file.\n', error);
     new Error(`Invalid .kktrc.js file. \n ${message}`);
     process.exit(1);
diff --git a/core/tsconfig.json b/core/tsconfig.json
index ed061fa2e..b5a8bfd31 100644
--- a/core/tsconfig.json
+++ b/core/tsconfig.json
@@ -1,16 +1,16 @@
 {
   "compilerOptions": {
     "module": "commonjs",
-    "esModuleInterop": true,
-    "skipLibCheck": true,
+    "target": "ES5",
+    "strict": true,
     "declaration": true,
-    "target": "es2017",
-    "noImplicitAny": true,
+    "esModuleInterop": true,
     "resolveJsonModule": true,
     "moduleResolution": "node",
-    "sourceMap": true,
+    "skipLibCheck": true,
+    "noImplicitAny": true,
     "outDir": "lib",
     "baseUrl": "."
   },
-  "include": ["src/**/*", "src/*"]
+  "include": ["src/**/*"]
 }
diff --git a/packages/less-modules/package.json b/packages/less-modules/package.json
index 95943e184..a8991ac66 100644
--- a/packages/less-modules/package.json
+++ b/packages/less-modules/package.json
@@ -18,6 +18,7 @@
     "src"
   ],
   "scripts": {
+    "build": "tsbb build --no-esm",
     "watch": "tsbb watch --no-esm"
   },
   "dependencies": {
diff --git a/packages/less-modules/src/index.ts b/packages/less-modules/src/index.ts
index 7eb38bac8..425788b1a 100644
--- a/packages/less-modules/src/index.ts
+++ b/packages/less-modules/src/index.ts
@@ -104,7 +104,7 @@ const createLessModule = (lessLoaderOptions = {} as LessLoaderOptions) => {
 /**
  * Use create-react-app to build react libraries. Support for regular less files and *.module.less files.
  */
-const module = createLessModule();
-(module as any).withLoaderOptions = createLessModule;
+const lessmodule = createLessModule();
+(lessmodule as any).withLoaderOptions = createLessModule;
 
-export default module;
+export default lessmodule;
diff --git a/packages/resolve-fallback/package.json b/packages/resolve-fallback/package.json
index 28da9735d..e5df073dd 100644
--- a/packages/resolve-fallback/package.json
+++ b/packages/resolve-fallback/package.json
@@ -23,6 +23,7 @@
   "dependencies": {
     "assert": "^2.0.0",
     "crypto-browserify": "^3.12.0",
+    "path-browserify": "^1.0.1",
     "https-browserify": "^1.0.0",
     "os": "^0.1.2",
     "os-browserify": "^0.3.0",