Ggtcf

I've got some quite interesting issue while I was trying to add webpack-notifier plugin to a brand new Angular 7 application. The idea was to keep ng build --watch running in a console and have a balloon notifications if the current build fails (or restored back from the failed state).

TL;DR;

When running ng build --watch, the array of errors for the webpack done compiler hook could be empty even if the build has failed. Is there any workaround for this if I need the errors array to show the broken build notification?

Now the details.

At first, I've created a new Angular project using ng new my-app
Then I've added a custom webpack config by following ngx-build-plus instructions from here.
Then I've taken a webpack-notifier source and used it in webpack.partial.js as

module.exports = 
 plugins: [
 new WebpackNotifierPlugin()
 ]

Let's try it: ng build --watch --extra-webpack-config webpack.partial.js

Okay, everything works fine, let's break the build by adding some nonsense to, say, app.component.ts. As expected, I can see an error in console and a popup notification by the notifier plugin. Now, I revert the breaking changes back, wait for build to turn green and add breaking changes again.

As a result, I have an error message in console, but no popup error notification.

Let's go deeper. WebpackNotifierPlugin uses webpack compiler hooks:

WebpackNotifierPlugin.prototype.apply = function(compiler) 
 if (compiler.hooks) 
 var plugin = name: 'Notifier' ;

 compiler.hooks.done.tap(plugin, this.compilationDone.bind(this));
 else 
 compiler.plugin('done', this.compilationDone.bind(this));
 
;

WebpackNotifierPlugin.prototype.compilationDone = function(stats) 
 // read the stats and show the message

Webpack done hook has one stats parameter and notifier plugin expects stats.compilation.errors array to contain, well, errors. But if I'll log it to the output:

WebpackNotifierPlugin.prototype.compilationDone = function(stats) 
 console.log('Errors: ')
 console.info(stats.compilation.errors);
;

it turns out that stats.compilation.errors could be empty even if there are errors in console:

Do you have any ideas on the cause of such behaviour and whether there's any workaround?

The reason of such a behaviour is that forked type checker doesn't pass semantic errors down the line. As a workaround one may add "forkTypeChecker": false to the build options (its projects.[app-name].achitect.build.options part of the angular.json)

A bit more detailed description could be found in the Angular CLI issue tracker:
https://github.com/angular/angular-cli/issues/13870