xxxx.sandbox.ts is missing from the TypeScript compilation.

[wisespace-io]

Versions

6.2.0

Angular CLI: 8.3.25
Node: 12.14.1
OS: win32 x64
Angular: 8.2.14
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router

Package                            Version
------------------------------------------------------------
@angular-devkit/architect          0.803.25
@angular-devkit/build-angular      0.803.25
@angular-devkit/build-ng-packagr   0.803.25
@angular-devkit/build-optimizer    0.803.25
@angular-devkit/build-webpack      0.803.25
@angular-devkit/core               8.3.25
@angular-devkit/schematics         8.3.25
@angular/cli                       8.3.25
@angular/material                  8.2.3
@ngtools/webpack                   8.3.25
@schematics/angular                8.3.25
@schematics/update                 0.803.25
ng-packagr                         5.7.1
rxjs                               6.4.0
typescript                         3.5.3
webpack                            4.39.2

Repro steps

• ng add angular-playground
• npm run playground
• add a .sandbox.ts file to the project

Observed Behavior

notifications.component.sandbox.ts is missing from the TypeScript compilation. Please make sure it is in your tsconfig via the 'files' or 'include' property.
at AngularCompilerPlugin.getCompiledFile (...\node_modules@ngtools\webpack\src\angular_compiler_plugin.js:913:23)
at \node_modules@ngtools\webpack\src\loader.js:41:31
at runMicrotasks ()
at processTicksAndRejections (internal/process/task_queues.js:94:5)

Desired Behavior

be able to select the component from the sandbox UI

Any other details that may be useful (optional)

[andradf]

While I'm not sure if this was the cause for the original poster, I had the same issue and in the end, after an hour wasted, I figured out that I was running npm start playground instead of the correct npm run playground. Hope this helps someone else.