[REVIEW 3-6] fix for fdo#56983 , protect against invalid files during cond format import

[Markus Mohrhard]

Hey,

[1] fixes a problem that an invalid file without a cond format range
will result in a crash the next time we update conditional formats.
The easiest solution is to delete all conditional formats that don't
have a range after import to prevent this problem.

Regards,
Markus

[1] http://cgit.freedesktop.org/libreoffice/core/commit/?id=eb240530443b964ea45bf80a5e3711e11a3f09c5