Validation error message: "An error occurred while attempting to extract the target object of type ‘System.Activites.InArgument’ from the method call expression <activity><property>.Get"

When using the (non-Generic) version of InArgument, you may see the following error message during validation: The private implementation of activity ‘<activity>’ has the following validation error: “An error occurred while attempting to extract the target object of type ‘System.Activites.InArgument’ from the method call expression <activity><property>.Get”. Note that the expression determining the object of type…