ProjectManager: Report more errors

Task-number: QTCREATORBUG-10844
Change-Id: Ia89a17a5098fb1e2180b32d4c54a61f4ef5b0fbb
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Daniel Teske <daniel.teske@digia.com>