Fixed some auto tests

In the listmodel test an error description was not converted to a
string.
In the pathview test, number literals are always interpreted as double,
but qreal can also be float, which lead to failing tests. Constructor
usage prevents "expected data of type 'float', got 'double'".

Change-Id: I0c760486de0ba4df6a5e9a33e9528ca7d7a1a63e
Reviewed-by: Alan Alpert <aalpert@blackberry.com>