Angular upgrade - Error: inject() must be called from an injection context at...

I have an angular project structured like so:

Site1

• Module1
• Module2
• SharedModule <- NOT in a library, just a module

Site2

• Module3
• Module4
• SharedModule <- calls module in Main directly

I know this isn't ideal, but it's how it is.

The package.json files are exactly the same apart from the names of the application.

The project was started on Angular 8 and has always upgraded well, but going from 11 -> 12 I'm having issues:

Site1 builds fine and runs nicely. Site2 builds fine, but errors immediately on running with

Error: inject() must be called from an injection context at injectInjectorOnly (core:4745) at Module.ɵɵinject (core:4755) at Object.RouterModule_Factory [as factory] (router:5999) at R3Injector.hydrate (core.js:11438) at R3Injector.get (core.js:11257) at core.js:11295 at Set.forEach () at R3Injector._resolveInjectorDefTypes (core.js:11295) at new NgModuleRef$1 (core.js:25325) at NgModuleFactory$1.create (core.js:25379)
​

As Site1 works fine, I assume it must be something in calling that SharedModule?

I've tried adding "preserveSymlinks": true, to projects.$name.architect.build.options, but that doesn't work. I'm not using npm link as the other module isn't a library (I know it should have been set up that way, but it isn't).

I've spent at least 2 days trying to get this to work (obviously checking posts such as this and this, but the answers there dont seem to work.

Does anyone know how to fix this, or at least how to debug it please?

Continue reading...