Error: NG0203 when using RouterModule in Angular library

I'm trying to create an Angular v14 application that imports an Angular library that contains routing. My setup looks something like this:

app.module.ts: (Main app)

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    RouterModule.forRoot([
      {path: '' , loadChildren: () => import('@mytest/core').then(m => m.TestModule)}
    ])
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

test.module.ts (Library)

@NgModule({
  imports: [
    CommonModule,
    RouterModule.forChild([
      {path: '', pathMatch: 'full', component: TestComponentComponent}
    ]),
  ],
  declarations: [TestComponentComponent],
  exports: [TestComponentComponent],
})
export class TestModule { }

When I run ng serve everything compiles without any issue, however opening localhost:4200 I find a blank page and this error in the console:

Error: NG0203: inject() must be called from an injection context such as a constructor, a factory function, a field initializer, or a function used with `EnvironmentInjector#runInContext`.

If I omit the RouterModule.forChild() in test.module.ts the error dissappears, so it must be related to that (also, the stacktrace references RouterModule_Factory). I also have the same issue with the NGRX StoreModule.forFeature() when I try to use that. I've made sure to use all the same versions of @angular/..., since a version mismatch seems to cause this error in some instances, but that doesn't change anything.

Any ideas on what I'm missing?