Prevent qWarning() messages that can arise when browsing samba shares:
```
QFileInfo::absolutePath: Constructed with empty filename
QFileInfo::absolutePath: Constructed with empty filename
QFileInfo::absolutePath: Constructed with empty filename
# possibly many more
```
The source of the empty paths isn't clear (see the backtrace in the "Test Plan"); I never noticed the warnings until I upgraded kio-extras to 19.04.3 and Samba to 4.8.9 and my MSWin rig to Win10 1903.
It's probably a good idea to handle this case gracefully.