Errors in child compilers not reported, process exits without info

[nadavsinai]

🐞 Bug report

Command (mark with an x)

• new
• build
• serve
• test
• e2e
• generate
• add
• update
• lint
• xi18n
• run
• config
• help
• version
• doc

Is this a regression?

Yes, the previous version in which this bug was not present was: ....

no

Description

If a compilation includes child compilations as is the case when using worker-loader for example (or many other webpack loaders/plugins) the build process can fail and exit without providing any info but the exit code being 1.

🔬 Minimal Reproduction

clone this, run ng build, no errors will be shown except of non-0 exit code or "failed to compile" in serve mode.
anything with a child compiler emits errors into it's own errors object.
you code in createBrowserLoggingCallback
which delegates to (stats.hasErrors() does not take into account the possibility of errors in child compilers.

🔥 Exception or Error

the problem is the the error is not shown ;-)

🌍 Your Environment

Angular CLI: 8.3.23
Node: 12.16.2
OS: win32 x64
Angular: 8.2.14
... animations, common, compiler, compiler-cli, core, elements
... forms, language-service, platform-browser
... platform-browser-dynamic, platform-server, router

Package                            Version
------------------------------------------------------------
@angular-devkit/architect          0.803.23
@angular-devkit/build-angular      0.803.23
@angular-devkit/build-ng-packagr   0.803.26
@angular-devkit/build-optimizer    0.803.23
@angular-devkit/core               8.3.23
@angular-devkit/schematics         8.3.23
@angular/cdk                       8.2.3
@angular/cli                       8.3.23
@angular/flex-layout               8.0.0-beta.27
@schematics/angular                8.3.23
@schematics/update                 0.803.23
ng-packagr                         5.7.1
rxjs                               6.5.5
typescript                         3.5.3
webpack                            4.29.6

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