UnhandledPromiseRejectionWarning when compiling broken SCSS with aot=true

[devoto13]

🐞 Bug report

Command (mark with an x)

- [x] build
- [x] serve

Is this a regression?

Not sure.

Description

ng serve does not handle invalid SCSS gracefully in AOT mode. See minimal reproduction for more details.

🔬 Minimal Reproduction

$ ng new --style scss test-app
$ ng serve --aot

Wait until it completes, then open src/app/app.component.scss and add any invalid code, like .rule (note missing brackets).

Observe UnhandledPromiseRejectionWarning in the terminal.

In JIT mode it gives a helpful error message instead:

ERROR in ./src/app/app.component.scss
Module build failed (from ./node_modules/sass-loader/lib/loader.js):

.rule
    ^
      Expected "{".
  ╷
1 │ .rule
  │      ^
  ╵

🔥 Exception or Error

(node:43977) UnhandledPromiseRejectionWarning: TypeError: Cannot destructure property `warnings` of 'undefined' or 'null'.
    at /Users/devoto13/Projects/trash/test-app/node_modules/@ngtools/webpack/src/resource_loader.js:81:23
    at /Users/devoto13/Projects/trash/test-app/node_modules/webpack/lib/Compiler.js:659:23
    at /Users/devoto13/Projects/trash/test-app/node_modules/webpack/lib/Compilation.js:1379:13
    at eval (eval at create (/Users/devoto13/Projects/trash/test-app/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:12:1)
    at /Users/devoto13/Projects/trash/test-app/node_modules/@ngtools/webpack/src/resource_loader.js:70:39
    at processTicksAndRejections (internal/process/task_queues.js:85:5)

🌍 Your Environment

Angular CLI: 8.2.0
Node: 12.7.0
OS: darwin x64
Angular: 8.2.0
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.802.0
@angular-devkit/build-angular     0.802.0
@angular-devkit/build-optimizer   0.802.0
@angular-devkit/build-webpack     0.802.0
@angular-devkit/core              8.2.0
@angular-devkit/schematics        8.2.0
@ngtools/webpack                  8.2.0
@schematics/angular               8.2.0
@schematics/update                0.802.0
rxjs                              6.4.0
typescript                        3.5.3
webpack                           4.38.0

Anything else relevant?

[jcox86]

+1 Also getting this on valid scss (as far as I can tell) when upgrading an existing, working project from 7.1.4 to 8.2.0. ng build works fine. --aot flag breaks with the aforementioned error.

Additional error message below:
(node:6128) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2) (node:6128) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated.

[akopchinskiy]

Same error