Dev server error is present when template error is fixed

[dereklin]

The issue is caused by package @angular/....

"@angular/animations": "~10.1.4",
"@angular/common": "~10.1.4",
"@angular/compiler": "~10.1.4",
"@angular/core": "~10.1.4",
"@angular/forms": "~10.1.4",
"@angular/platform-browser": "~10.1.4",
"@angular/platform-browser-dynamic": "~10.1.4",
"@angular/router": "~10.1.4",
"rxjs": "~6.6.0",
"tslib": "^2.0.0",
"zone.js": "~0.10.2"

Description

Dev server error is present when template error is fixed

🔬 Minimal Reproduction

install the latest version of @angular/cli

I am using

"@angular/cli": "~10.1.4",

create a brand new app like

ng new my-new-app

In app.component.html, copy and paste the following line inside of the main content div:

<h1 [style.color]="'red'">Hello World!</h1>

Change the first double quote to single quote to cause the template error. Then change it back to double quote to fix it.

In the terminal, these errors are shown:

    ERROR in src/app/app.module.ts:9:5 - error NG6001: The class 'AppComponent' is listed in the declarations of the NgModule 'AppModule', but is not a directive, a component, or a pipe. Either remove it from the NgModule's declarations, or add an appropriate Angular decorator.
    
    9     AppComponent
          ~~~~~~~~~~~~
    
      src/app/app.component.ts:8:14
        8 export class AppComponent {
                       ~~~~~~~~~~~~
        'AppComponent' is declared here.
    src/app/app.component.html:417:25 - error NG8002: Can't bind to 'ngSwitch' since it isn't a known property of 'div'.
    
    417   <div class="terminal" [ngSwitch]="selection.value">
                                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    
      src/app/app.component.ts:5:16
        5   templateUrl: './app.component.html',
                         ~~~~~~~~~~~~~~~~~~~~~~
        Error occurs in the template of component AppComponent.
    src/app/app.component.html:535:1 - error NG8001: 'router-outlet' is not a known element:
    1. If 'router-outlet' is an Angular component, then verify that it is part of this module.
    2. If 'router-outlet' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.
    
    535 <router-outlet></router-outlet>
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    
      src/app/app.component.ts:5:16
        5   templateUrl: './app.component.html',
                         ~~~~~~~~~~~~~~~~~~~~~~
        Error occurs in the template of component AppComponent.

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🌍 Your Environment

It's a brand new angular app as of 10/6/2020:

"dependencies": {
"@angular/animations": "~10.1.4",
"@angular/common": "~10.1.4",
"@angular/compiler": "~10.1.4",
"@angular/core": "~10.1.4",
"@angular/forms": "~10.1.4",
"@angular/platform-browser": "~10.1.4",
"@angular/platform-browser-dynamic": "~10.1.4",
"@angular/router": "~10.1.4",
"rxjs": "~6.6.0",
"tslib": "^2.0.0",
"zone.js": "~0.10.2"
},
"devDependencies": {
"@angular-devkit/build-angular": "~0.1001.4",
"@angular/cli": "~10.1.4",
"@angular/compiler-cli": "~10.1.4",
"@types/node": "^12.11.1",
"@types/jasmine": "~3.5.0",
"@types/jasminewd2": "~2.0.3",
"codelyzer": "^6.0.0",
"jasmine-core": "~3.6.0",
"jasmine-spec-reporter": "~5.0.0",
"karma": "~5.0.0",
"karma-chrome-launcher": "~3.1.0",
"karma-coverage-istanbul-reporter": "~3.0.2",
"karma-jasmine": "~4.0.0",
"karma-jasmine-html-reporter": "^1.5.0",
"protractor": "~7.0.0",
"ts-node": "~8.3.0",
"tslint": "~6.1.0",
"typescript": "~4.0.2"
}

[JoostK]

The issue here is that template parse errors result in the whole component being invalid, causing the NgModule declaration to also be flagged as invalid. This causes the implicit dependency from app.module.ts to app.component.html not to be registered, such that fixing the template does not invalidate the captured state for app.module.ts that still contains the error.

[JoostK]

This has been fixed in #39967 and will be part of the 11.0.4 release, somewhere next week.

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