Even though the emoji panel may be destroyed with the OSK, the swipeTracker
that is set up to navigate between pages is left lingering, and handling
events for some gestures in the stage. This results in warnings like:
JS ERROR: TypeError: this._panel is null
set delta@resource:///org/gnome/shell/ui/keyboard.js:720:9
_onSwipeUpdate@resource:///org/gnome/shell/ui/keyboard.js:750:22
_updateGesture@resource:///org/gnome/shell/ui/swipeTracker.js:670:14
vfunc_gesture_progress@resource:///org/gnome/shell/ui/swipeTracker.js:288>
on touch interaction after the OSK was shown and dismissed. In order to fix
this, issue explicit destruction of the swipeTracker when the emoji pager
actor is destroyed.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2543>