The exception was not very informative about why exactly the
error message may occur. Weston in Debian buster doesn't
support the stable XDG Shell protocol, for instance, and
triaging this took some effort.
This now results in windows being painted on the screen. However, input is
still ending up in all the wrong places, and there is a lot of garbage content
being painted outside the actual windows.
Right clicking on a window seems to trigger rotate behavior, which needs to
be evaluated and likely removed (or prevented, if this is done by Weston).
Interestingly, checking for ->configured on first surface commit also seems to
break the backend.
Rearranging order of the code, freeing some memory, writing a note
that additional work is required, returning a value through pointer
passed as argument, etc.
