ViewCatalog::resolveView() may return invalid resolved view on encountering invalid namespace in view definition

The ViewCatalog::_lookup_inlock() method will return a null shared_ptr if either:

1. A view definition is not found for the given namespace
2. A view catalog reload is needed and the given namespace is not a valid collection name

ViewCatalog::resolveView() however interprets the null shared_ptr as an indication that the namespace is a collection and returns the resolved view. This is incorrect in the case that ViewCatalog::_lookup_inlock() returns due to invalid collection name