Merge pull request #14 from mskorzhinskiy/fix/dont-barf-on-null

fix: don't barf with a null metaWindow

Context from @mskorzhinskiy in [PR #14]:

> Using next-release branch of PaperWM-community on Gnome 40, I have
> noticed that some of the keybindings do not work for some reason. E.g.
> "Super+V", whic should open the calendar/notifications widget. Every
> hit of this keybinding additionally leads to a JS stack trace in the
> gnome journal.

> This fix doesn't bring back the functionality, i.e. keybindigs are
> still not working (I know about Super+V and Super+S), but it removes
> the annoying stack trace.

[PR #14]: #14

tiling.js

@@ -3283,6 +3283,9 @@ function slurp(metaWindow) {
 }
 
 function barf(metaWindow) {
+    if (!metaWindow)
+        return;
+
     let space = spaces.spaceOfWindow(metaWindow);
     let index = space.indexOf(metaWindow);
     if (index === -1)