Inject migration does not work in a multi-project workspace

[kaiosales]

Which @angular/* package(s) are the source of the bug?

core

Is this a regression?

No

Description

In multi-project workspace, the inject migration doesn't work when targeting one of the projects due to either not finding any files in other projects or considering them external thus it throws a SchematicsException

Minimal Reproduction

1. Create a new workspace with Angular CLI
   a. ng new my-workspace --no-create-application
2. Generate a new application in the workspace
   a. ng generate application my-app
3. Generate a new library in the workspace
   a. ng generate library my-lib
4. Create a new service
5. Import service into generated component in my-lib
6. Run inject migration targeting the library
   a. ng generate @angular/core:inject --path=./projects/my-lib/src

Please provide a link to a minimal reproduction of the bug

https://stackblitz.com/edit/stackblitz-starters-ap2u31fu

Please provide the exception or error you saw

`Could not find any files to migrate under the path \\home\\projects\\stackblitz-starters-ap2u31fu\\projects\\my-lib\\src. Cannot run the inject migration.`

Please provide the environment you discovered this bug in (run ng version)

Angular CLI       : 21.0.3
Angular           : 21.0.5
Node.js           : 20.19.1
Package Manager   : npm 10.8.2
Operating System  : linux x64

 
Package				Version
------------------------------------------------
@angular/build			 21.0.3
@angular/cli			 21.0.3
@angular/common			 21.0.5
@angular/compiler		 21.0.5
@angular/compiler-cli		 21.0.5
@angular/core			 21.0.5
@angular/forms			 21.0.5
@angular/platform-browser	 21.0.5
@angular/router			 21.0.5
ng-packagr			 21.0.0
rxjs				 7.8.2
typescript			 5.9.3
vitest				 4.0.15

Anything else?

I couldn't find any information if this multi-project scenario are supported by migrations so I'm not sure if this is a bug or not.

One thing I noticed is that in the source code the exception is thrown if no files are found, so maybe a naïve fix could be just rendering a warning but continue to the next tsconfig file so that the whole migration process isn't interrupted (however it might still ignores due to the external library check)

Alternatives considered

In a similar but now deprecated migration made by @eneajaho in the ngxtension project it contains a --project flag which could be a nice solution
https://ngxtension.dev/utilities/migrations/inject-migration/#options

[aparzi]

The problem appears to be caused by the way the various tsconfig files are parsed when the path option is passed. This migration seems to handle the files to be parsed differently than the controlFlow migration (even when the path option is passed), which, for example, works.
I'll try changing the way the files are parsed; I'm working on it.