Recently I am doing my side project using Hybrid framework Ionic2.
Ionic2 has a CLI tool and the command "ionic serve" can start your local server and watch your local changes.

After some code refactoring, I tried to run "ionic serve" and hoping ionic could start the local server as usual, but the local server failed to run without giving any error info.

[WARN] Detected @ionic/cli-plugin-ionic-angular in your package.json.

       As of CLI 3.8, it is no longer needed. You can uninstall it:

       npm uninstall -D @ionic/cli-plugin-ionic-angular


Starting app-scripts server: --address 0.0.0.0 --port 8100 --livereload-port 35729 --dev-logger-port 53703 --nobrowser -
Ctrl+C to cancel
[21:18:22]  watch started ...
[21:18:22]  build dev started ...
[21:18:22]  clean started ...
[21:18:22]  clean finished in 14 ms
[21:18:22]  copy started ...
[21:18:22]  transpile started ...
[21:18:25]  transpile finished in 2.98 s
[21:18:25]  preprocess started ...
[21:18:25]  deeplinks started ...
[21:18:25]  deeplinks finished in 88 ms
[21:18:25]  preprocess finished in 92 ms
[21:18:25]  webpack started ...
[21:18:25]  copy finished in 3.31 s

And when I run this command "npm run ionic:serve"
It gave me the following error

> cutePuppyPics@0.0.1 ionic:serve F:\Projects\EazeTrade
> ionic-app-scripts serve

[21:20:10]  ionic-app-scripts 1.3.7
[21:20:10]  watch started ...
[21:20:10]  build dev started ...
[21:20:10]  clean started ...
[21:20:10]  clean finished in 3 ms
[21:20:10]  copy started ...
[21:20:10]  transpile started ...
[21:20:13]  transpile finished in 2.96 s
[21:20:13]  preprocess started ...
[21:20:13]  deeplinks started ...
[21:20:13]  deeplinks finished in 85 ms
[21:20:13]  preprocess finished in 89 ms
[21:20:13]  webpack started ...
[21:20:13]  copy finished in 3.31 s

TypeError: Data must be a string or a buffer
    at TypeError (native)
    at Hash.update (crypto.js:74:16)
    at HarmonyExportImportedSpecifierDependency.updateHash (F:\Projects\EazeTrade\node_modules\webpack\lib\dependencies\HarmonyExportImportedSpecifierDependency.js:151:8)
    at F:\Projects\EazeTrade\node_modules\webpack\lib\DependenciesBlock.js:33:5
    at Array.forEach (native)
    at NormalModule.DependenciesBlock.updateHash (F:\Projects\EazeTrade\node_modules\webpack\lib\DependenciesBlock.js:32:20)
    at NormalModule.Module.updateHash (F:\Projects\EazeTrade\node_modules\webpack\lib\Module.js:162:41)
    at NormalModule.updateHash (F:\Projects\EazeTrade\node_modules\webpack\lib\NormalModule.js:327:30)
    at modules.forEach.m (F:\Projects\EazeTrade\node_modules\webpack\lib\Chunk.js:253:31)
    at Array.forEach (native)

npm ERR! Windows_NT 10.0.14393
npm ERR! argv "F:\\NodeJs\\node.exe" "F:\\NodeJs\\node_modules\\npm\\bin\\npm-cli.js" "run" "ionic:serve"
npm ERR! node v6.11.0
npm ERR! npm  v3.10.10
npm ERR! code ELIFECYCLE
npm ERR! cutePuppyPics@0.0.1 ionic:serve: `ionic-app-scripts serve`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the cutePuppyPics@0.0.1 ionic:serve script 'ionic-app-scripts serve'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the cutePuppyPics package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     ionic-app-scripts serve
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs cutePuppyPics
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!     npm owner ls cutePuppyPics
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     F:\Projects\EazeTrade\npm-debug.log

But this does not offer much help about this issue. Finally I found this answer from Github
https://github.com/webpack/webpack/issues/4072

Then I got the error info

File not found:  HarmonyImportDependency {
  module: null,
  request: './customer',
  userRequest: './customer',
  range: [ 153, 191 ],
  importedVar: '__WEBPACK_IMPORTED_MODULE_4__customer__',
  loc:
   SourceLocation {
     start: Position { line: 5, column: 0 },
     end: Position { line: 5, column: 38 } } }
crypto.js:74
  this._handle.update(data, encoding);

It turns out I forgot import the customer.ts file.