Function validateProvider

packages/core/src/di/provider_collection.ts:365–386

(
  provider: SingleProvider,
  providers: Array<SingleProvider | InternalEnvironmentProviders>,
  containerType: Type<unknown>,
)

}

function validateProvider(
  provider: SingleProvider,
  providers: Array<SingleProvider | InternalEnvironmentProviders>,
  containerType: Type<unknown>,
): void {
  if (
    isTypeProvider(provider) ||
    isValueProvider(provider) ||
    isFactoryProvider(provider) ||
    isExistingProvider(provider)
  ) {
    return;
  }

  // Here we expect the provider to be a `useClass` provider (by elimination).
  const classRef = resolveForwardRef(
    provider && ((provider as StaticClassProvider | ClassProvider).useClass || provider.provide),
  );
  if (!classRef) {
    throwInvalidProviderError(containerType, providers, provider);
  }
}

function deepForEachProvider(
  providers: Array<Provider | InternalEnvironmentProviders>,