Enable more compile warnings

and fix the fallout detected.

.gitlab/issue_templates/bug.md

+# What problem did you encounter
+
+## What is the current behaviour?
+
+## What is the expected behaviour?
+
+## How to reproduce
+
+  Please provide steps to reproduce the issue. If it's a graphical issue please
+  attach screenshot.
+
+# Which version did you encounter the bug in?
+
+ - [ ] I Compiled it myself. If you compiled phosh from source please provide the
+   git revision via e.g. by running ``git log -1 --pretty=oneline`` and pasting
+   the output below.
+
+ - [ ] I used the precompiled Debian package (e.g. by running a prebuilt
+   image). Please paste the output oof ``dpkg -s phosh`` below.
+
+```
+  Phosh Version:
+```
+
+# What hardware are you running phosh on?
+
+ - [ ] amd64 qemu image
+ - [ ] Librem5 devkit
+ - [ ] nested compositor. If so please give the full command you start phosh
+   with.
+ - [ ] other (please elaborte)
+
+# Releveant logfiles
+
+  Please provide relevant logs. You can e.g. the logs since last boot read
+  with ``journalctl -b 0``.