Importing an empty namespace should be an error

If you accidentally import Qt 1.0, or Qt 4.5 (before Declarative modules were provided) the only error is that types cannot be found. While it's reasonable to expect them to check the module documentation to verify the version number, this is an obvious error which we could help diagnose.

The compiler could provide warnings in these circumstances such as
import QT 4.7 :Namespace QT cannot be found
import Qt 1.0 : No types found in version 1.0 of Qt
or
import Qt 1.0 : No types found in version 1.0 of Qt. The initial version of Qt is 4.6