@CustomShadowVariable with a variableListenerRef to something that isn't a custom shadow variable, should fail fast with a clear error message.

See https://stackoverflow.com/questions/72487658/custom-shadow-variables-are-not-updating-when-visit-change-to-one-chainvehicle/72489047#72489047

Requirements:

• fail fast if X field Y variableListenerRef=z has a z that isn't a custom shadow variable
• Clear error message mentioning context of X.y + z isn't a custom shadow variable.