skip over supposed network shares that aren't
Summary:
we explicitly request listFromType(Solid::DeviceInterface::NetworkShare)
but apparently still can get devices that aren't actually of that type.
add an explicit type check to guard against bogus shares coming out of
listFromType.
CCBUG: 419220
Test Plan: mount an overlay (I am guessing that's what the problem with kubuntu is), observe no crash on init
Reviewers: ngraham
Reviewed By: ngraham
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D28275