If a device fails to open during the plugin startup, we exit the handler
constructor early and leave the d member as nullptr.
However the recently added m_handler->isFiltered() call after m_handler
is instantiated assumes that d is always valid, which triggers a crash
in the forementionned situation. Fix it to check for d's validity first.
This can occur when a device is connected then disconnected right after,
so that it's gone by the time we get the notification from udev.
Change-Id: Ia755868338f92b91c181be8557e06e087d70fcc6
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
d0acd26c37