systemActions: Filter out empty (folded) terms

We split the search string into words using whitespace, while
GLib.tokenize_and_fold() splits on any non-alphanumeric characters.

That is, a valid search term like ',' will be tokenized as [], so
the original non-empty terms may get mapped to an empty array.

And as [].every() returns true for any condition[0], we end up
matching *all* system actions in that case. We want the exact
opposite and not return any results, so handle that case explicitly.

[0] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every

https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3169

js/misc/systemActions.js

@@ -269,6 +269,10 @@ const SystemActions = GObject.registerClass({
         terms = terms.map(
             term => GLib.str_tokenize_and_fold(term, null)[0]).flat(2);
 
+        // tokenizing may return an empty array
+        if (terms.length === 0)
+            return [];
+
         let results = [];
 
         for (let [key, { available, keywords }] of this._actions) {