Proposal: detect the absence of the `node_modules` folder while running `ng build` or `ng serve`

[AndrewKushnir]

🚀 Feature request

Command

• build
• serve

Description

Running ng build or ng serve in a folder without node_modules present results in the following error thrown in terminal:

$ ng serve
An unhandled exception occurred: Cannot find module '@angular-devkit/build-angular/package.json'
Require stack:
... stacktrace ...
See "/private/var/folders/7d/r6b3nrdj7bn9t_w_dclm6y9r00kg80/T/ng-PRpMHw/angular-errors.log" for further details.

This can happen for example after downloading an example app from angular.io website. Example link:

https://angular.io/generated/zips/form-validation/form-validation.zip

Describe the solution you'd like

The proposal is to handle the case when node_modules folder is not present and output a user-friendly error message that would suggest to run npm install or yarn install.

[sahilpurav]

Instead of showing a message, how if we automatically do npm install or yarn install

[helloankit]

Such errors seems to be mind-boggling when I was very new to Angular.
These needs to be exact and clear to the end user.

[elvisbegovic]

Same with ng new ap --skip-install && cd ap && ng version

This is somehow related to #10474

[alan-agius4]

Duplicate of #10536

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