keepassxc: segfault at error 4 in libQt5WaylandClient

Downstream bug-report

It is very easily replicable acually now for me.

1. I start keepassxc.
2. I plug an external monitor through a USB-C docking station from DELL.
3. I disable the local screen in sway to force all output to external screen.
4. I unplug external screeen.
5. I enable local screen again.

And somewhere between start of 4. and end of 5. keepassxc crashes.
I did a `date` right before (4.): Mon May 6 10:26:15 CEST 2019
And I did a `date` right after (5.): Mon May 6 10:26:31 CEST 2019

The timestamp of the crash in syslog is 10:26:18 ... so 1-2 seconds after I unplugged... but that's probably the time for udev +kernel to process the unplug event...

So it's in link with (4.), not (5.)

In any case here is the syslog (jouranctl) of the crash:
```
May 06 10:26:18 huit kernel: keepassxc[2818]: segfault at 0 ip 00007f7f459125ca sp 00007ffd2d6bef50 error 4 in libQt5WaylandClient.so.5.12.3[7f7f4590c000+82000]
May 06 10:26:18 huit kernel: Code: 78 14 04 7e 13 31 db e9 43 ff ff ff 48 8b 7c 24 10 e8 9a f4 ff ff eb e3 48 89 df ff 15 f7 4e 0a 00 48 89 c7 ff 15 36 67 0a 00 <48> 8b 10 48 89 c7 ff 52 30 48 89 df 41 89 c6 67 e8 31 f7 ff ff 48
May 06 10:26:18 huit kernel: audit: type=1701 audit(1557131178.295:71): auid=1001 uid=1001 gid=1001 ses=6 pid=2818 comm="keepassxc" exe="/usr/bin/keepassxc" sig=11 res=1
May 06 10:26:18 huit audit[2818]: ANOM_ABEND auid=1001 uid=1001 gid=1001 ses=6 pid=2818 comm="keepassxc" exe="/usr/bin/keepassxc" sig=11 res=1
```

Here is the journalctl:
2019-05-06_journalctl.log

Here is the logfile created from launching keepassxc with aboves `WAYLAND_DEBUG=1`:
2019-05-06_keepassxc.log

Hope that helps. Please let me know. Thanks!!

Tormen