Error: No provider for ActiveCartService! - when extending CheckoutStepsSetGuard in Spartacus

Question

I am having the following errors when I try to override and extend the CheckoutStepsSetGuard :

ERROR Error: Uncaught (in promise): Error: Invalid CanActivate guard in cmsMapping
Error: Invalid CanActivate guard in cmsMapping
(...)
ERROR NullInjectorError: R3InjectorError(AppModule)[CheckoutStepsSetGuard -> > MyCheckoutStepsSetGuard -> ActiveCartService -> ActiveCartService -> ActiveCartService]: 
NullInjectorError: No provider for ActiveCartService!

Do you know what could be wrong ?

Answer 1

What this Angular Dependency Injection error might mean in the context of SAP Spartacus:

ERROR NullInjectorError: R3InjectorError(AppModule)[CheckoutStepsSetGuard -> MyCheckoutStepsSetGuard -> ActiveCartService -> ActiveCartService -> ActiveCartService]: 
NullInjectorError: No provider for ActiveCartService!

It looks that the ActiveCartService hasn't been provided yet, while it's already was attempted to be injected. I guess there is a race condition - we try to inject the service but the JS chunk with the cart functionality hasn't been lazy loaded yet (and the implementation of ActiveCartService wasn't provided yet).

I believe the remedy to such an issue is using the proxy ActiveCartFacade instead (Facade instead of Service). The Facade is a safe proxy object for accessing the ActiveCartService even when it's implementation not lazy loaded yet. Actually, calling any method of the ActiveCartFacade will implicitly trigger for you the lazy loading of the whole JS chunk with the cart functionality in the background, including the loading and providing of the the actual implementation of the ActiveCartService.

For more, see the official SAP Spartacus docs for Proxy Facades.