Beniamino Galvani authored May 07, 2020 and Thomas Haller committed Aug 28, 2020

Reported by coverity:

>>> CID 210228: Null pointer dereferences (REVERSE_INULL)
>>> Null-checking "dbobj" suggests that it may be null, but it has
    already been dereferenced on all paths leading to the check.

Fixes: ce0e898f ('libnm: refactor caching of D-Bus objects in NMClient')
(cherry picked from commit 272f1910)
(cherry picked from commit 144e7e40)