TypeDescriptor with Name '{0}' and Id '{1}' has the IsCollection flag set. The ReturnTypeDescriptor of a CheckAccess MethodInstance ...

TypeDescriptor with Name '{0}' and Id '{1}' has the IsCollection flag set. The ReturnTypeDescriptor of a CheckAccess MethodInstance must point to a scalar type that can be converted into an Int64. If multiple access check results are to be returned, the return TypeDescriptor must have an ancestor with the IsCollection flag set.