Error message when angular.json is invalid is not very descriptive

[rafidka]

Bug Report or Feature Request (mark with an x)

- [ ] bug report
- [x] feature request

Area

- [ ] devkit
- [ ] schematics

Versions

Output of ng --version:

Angular CLI: 6.0.8
Node: 9.8.0
OS: darwin x64
Angular: 6.0.4
... animations, common, compiler, compiler-cli, core, forms
... http, language-service, platform-browser
... platform-browser-dynamic, router

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.6.8
@angular-devkit/build-angular     0.6.8
@angular-devkit/build-optimizer   0.6.8
@angular-devkit/core              0.6.8
@angular-devkit/schematics        0.6.8
@angular/cli                      6.0.8
@ngtools/webpack                  6.0.8
@schematics/angular               0.6.8
@schematics/update                0.6.8
rxjs                              6.2.0
typescript                        2.7.2
webpack                           4.8.3

Repro steps

1. Create a new project: ng new test-angular
2. Edit angular.json and add some invalid input, for example add a comment to the first line.
3. Use the CLI to add a new module ng generate module New

The log given by the failure

Unexpected token / in JSON at position 0

Desired functionality

1. The message should be a little bit more descriptive. It is currently a bit difficult to understand the problem, and for new comers, it might seem there is a problem with the package instead of angular.json. Here are some issues which shows other users also had confusion about this:

#10843
#10938
#11103

2. Replace absolute position with line and line position. It doesn't help much if I get position 1277 and have to find out which line this is.

Example: Found an unexpected token / in angular.json in line 123 character 45.

This is much more descriptive and clearly tells the user that there is a problem in his/her angular.json file and the line where the error is found.

[rafidka]

Also, I just noticed #5610 which seems to have been addressed, which suggests comment should be allowed and the CLI should not complain about / characters in angular.json. Or am I missing something?

[sam-s4s]

This is very frustrating...

Invalid JSON character: "" at 0:0.
Error: Invalid JSON character: "" at 0:0.

Ummm... which file?

If I look at the error through a different text output, it reads:

Invalid JSON character: "" at 0:0.
Error: Invalid JSON character: "" at 0:0.

So I'm gonna have to open all the json files with a hex editor I guess... :/

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