customMenuFont was null, so objects was an empty array, and
NSDictionary throws an exception when being called with arrays
of different sizes.
Task-number: QTBUG-42728
Change-Id: I8cdab449fd8c1d12b65c46dd5617a7f5e3e96c6e
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@theqtcompany.com>