D6260: Better handle cases when the xkb keymap fails to be created

[Marco Martin]

mart accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R108 KWin

BRANCH
  safety-checks-xkbcommon-5.10

REVISION DETAIL
  https://phabricator.kde.org/D6260

To: graesslin, #kwin, #plasma, mart
Cc: plasma-devel, kwin, ZrenBot, spstarr, progwolff, lesliezhai, ali-mohamed, 
hardening, jensreuterberg, abetts, sebas, apol, mart, lukas