Karma hangs when using karma run

Versions

    _                      _                 ____ _     ___
   / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
  / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
 / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
/_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
               |___/
@angular/cli: 1.2.8 (e)
node: 8.8.1
os: linux x64
@angular/animations: 4.4.6
@angular/common: 4.4.6
@angular/compiler: 4.4.6
@angular/core: 4.4.6
@angular/forms: 4.4.6
@angular/http: 4.4.6
@angular/platform-browser: 4.4.6
@angular/platform-browser-dynamic: 4.4.6
@angular/router: 4.4.6
@angular/cli: 1.2.8
@angular/compiler-cli: 4.4.6
@angular/language-service: 4.4.6

Repro steps

• Create a new project with ng new <projectname>
• Open karma.conf.js and change autoWatch: true to autoWatch: false
• Spawn the test server with karma start
• Change styleUrls: ['./app.component.css'] to styleUrls: ['./app.comonent.css'] so the code is invalid and will trigger a webpack compilation error (typescript compile errors will have the same effect).
• Karma server will now error, this is fine.
• In another terminal, in the same directory execute karma run

Observed behavior

karma run now hangs untill the error is resolved.

Desired behavior

karma run should terminate with an error.

Mention any other details that might be useful (optional)

When configuring the project with the steps provided by the angular documentation this does not happen (https://angular.io/guide/webpack). This approach does not use the @Angular/cli so the problem seems to be in @Angular/cli

[sanderkoenders]

I could try to diagnose the problem and shoot in a pull-request if that would speed up the process. Just tell me whether this is a bug or intended behaviour in your point of view.

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