Crashes when monitor is disconnected

[thomashuss]

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I have a setup where I need to switch between two HDMI devices on one monitor using an external switch. When I switch away from my computer, the PaperWM extension crashes and freezes the entire shell. Switching away and back again brings the shell back to a usable state but PaperWM is no longer working, and displays "this.monitor is null" in a toast notification. This does not happen consistently and sometimes I can switch between inputs without it crashing. I can't figure out what exactly is causing it though.

I am on Manjaro 20.2 with Gnome 3.38.2 on X.Org, GTX 1050 Ti. Here is my journalctl when it crashes:

Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-1: Internal TMDS
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-1: 165.0 MHz maximum pixel clock
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0):
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-0: disconnected
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-0: Internal TMDS
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-0: 330.0 MHz maximum pixel clock
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0):
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-1: disconnected
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-1: Internal TMDS
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-1: 165.0 MHz maximum pixel clock
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0):
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-2: disconnected
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-2: Internal DisplayPort
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-2: 1440.0 MHz maximum pixel clock
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0):
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-3: disconnected
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-3: Internal TMDS
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0): DFP-3: 165.0 MHz maximum pixel clock
Dec 09 15:24:53 lucifer /usr/lib/gdm-x-session[1831]: (--) NVIDIA(GPU-0):
Dec 09 15:24:53 lucifer gnome-shell[1904]: JS ERROR: TypeError: monitor is null
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym 2f7259c9 with keysym 2f7259c9 (keycode 31).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff09 with keysym ff09 (keycode 17).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff57 with keysym ff57 (keycode 73).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff54 with keysym ff54 (keycode 74).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym 2f7259c9 with keysym 2f7259c9 (keycode 31).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym 6e with keysym 6e (keycode 39).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff56 with keysym ff56 (keycode 75).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff53 with keysym ff53 (keycode 72).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff52 with keysym ff52 (keycode 6f).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff51 with keysym ff51 (keycode 71).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff51 with keysym ff51 (keycode 71).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff50 with keysym ff50 (keycode 6e).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff54 with keysym ff54 (keycode 74).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff52 with keysym ff52 (keycode 6f).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff55 with keysym ff55 (keycode 70).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff53 with keysym ff53 (keycode 72).
Dec 09 15:24:53 lucifer gnome-shell[1904]: Window manager warning: Overwriting existing binding of keysym ff09 with keysym ff09 (keycode 17).
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:01 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:04 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:04 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:04 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:04 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:05 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:05 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:06 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:06 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:06 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:06 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: Usage of object.actor is deprecated for MessageTray
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
Dec 09 15:28:07 lucifer gnome-shell[1904]: Usage of object.actor is deprecated for MessageTray
Dec 09 15:28:07 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:08 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:08 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:08 lucifer gnome-shell[1904]: meta_display_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
Dec 09 15:28:08 lucifer gnome-shell[1904]: JS ERROR: TypeError: this._getPrimaryView() is null
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:08 lucifer gnome-shell[1904]: Can't update stage views actor StBin is on because it needs an allocation.
Dec 09 15:28:09 lucifer gnome-shell[1904]: Window manager warning: MetaSyncRing: Sync object is not ready -- were events handled properly?
Dec 09 15:28:09 lucifer gnome-shell[1904]: Window manager warning: MetaSyncRing: Sync object is not ready -- were events handled properly?
Dec 09 15:28:09 lucifer gnome-shell[1904]: Window manager warning: MetaSyncRing: Sync object is not ready -- were events handled properly?
Dec 09 15:28:09 lucifer gnome-shell[1904]: Window manager warning: MetaSyncRing: Too many reboots -- disabling
Dec 09 15:28:17 lucifer gnome-shell[1904]: Object Meta.BackgroundActor (0x55f7d7a62de0), has been already deallocated — impossible to access it. This might be caused by the object having been destroyed from C code using something such as destroy(), dispose(), or remove() vfuncs.
Dec 09 15:28:17 lucifer gnome-shell[1904]: clutter_actor_get_parent: assertion 'CLUTTER_IS_ACTOR (self)' failed
Dec 09 15:28:17 lucifer gnome-shell[1904]: == Stack trace for context 0x55f7d62e4200 ==
Dec 09 15:28:17 lucifer gnome-shell[1904]: #0   55f7da57d510 i   resource:///org/gnome/shell/ui/layout.js:845 (3908ac2dea60 @ 81)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #1   55f7da57d460 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:883 (21f252984d80 @ 87)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #2   55f7da57d2d0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:390 (21f252985880 @ 205)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #3   55f7da57d1b0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:634 (21f252985420 @ 625)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #4   55f7da57d0f0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:2306 (21f252983240 @ 90)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #5   7ffd5f50c3b0 b   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/utils.js:91 (d75e0d35f10 @ 38)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #6   55f7da57d068 i   resource:///org/gnome/shell/ui/main.js:248 (3908ac2bdce0 @ 12)
Dec 09 15:28:17 lucifer gnome-shell[1904]: == Stack trace for context 0x55f7d62e4200 ==
Dec 09 15:28:17 lucifer gnome-shell[1904]: #0   55f7da57d5f0 i   resource:///org/gnome/shell/ui/layout.js:897 (3908ac2de920 @ 149)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #1   55f7da57d510 i   resource:///org/gnome/shell/ui/layout.js:862 (3908ac2dea60 @ 401)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #2   55f7da57d460 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:883 (21f252984d80 @ 87)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #3   55f7da57d2d0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:390 (21f252985880 @ 205)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #4   55f7da57d1b0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:634 (21f252985420 @ 625)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #5   55f7da57d0f0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:2306 (21f252983240 @ 90)
Dec 09 15:28:17 lucifer gnome-shell[1904]: Object Meta.BackgroundActor (0x55f7d7a62de0), has been already deallocated — impossible to connect to any signal on it. This might be caused by the object having been destroyed from C code using something such as destroy(), dispose(), or remove() vfuncs.
Dec 09 15:28:17 lucifer gnome-shell[1904]: #6   7ffd5f50c3b0 b   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/utils.js:91 (d75e0d35f10 @ 38)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #7   55f7da57d068 i   resource:///org/gnome/shell/ui/main.js:248 (3908ac2bdce0 @ 12)
Dec 09 15:28:17 lucifer gnome-shell[1904]: == Stack trace for context 0x55f7d62e4200 ==
Dec 09 15:28:17 lucifer gnome-shell[1904]: #0   55f7da57d5f0 i   resource:///org/gnome/shell/ui/layout.js:899 (3908ac2de920 @ 200)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #1   55f7da57d510 i   resource:///org/gnome/shell/ui/layout.js:862 (3908ac2dea60 @ 401)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #2   55f7da57d460 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:883 (21f252984d80 @ 87)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #3   55f7da57d2d0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:390 (21f252985880 @ 205)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #4   55f7da57d1b0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:634 (21f252985420 @ 625)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #5   55f7da57d0f0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:2306 (21f252983240 @ 90)
Dec 09 15:28:17 lucifer gnome-shell[1904]: Object Meta.BackgroundActor (0x55f7d7a62de0), has been already deallocated — impossible to connect to any signal on it. This might be caused by the object having been destroyed from C code using something such as destroy(), dispose(), or remove() vfuncs.
Dec 09 15:28:17 lucifer gnome-shell[1904]: #6   7ffd5f50c3b0 b   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/utils.js:91 (d75e0d35f10 @ 38)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #7   55f7da57d068 i   resource:///org/gnome/shell/ui/main.js:248 (3908ac2bdce0 @ 12)
Dec 09 15:28:17 lucifer gnome-shell[1904]: == Stack trace for context 0x55f7d62e4200 ==
Dec 09 15:28:17 lucifer gnome-shell[1904]: #0   55f7da57d5f0 i   resource:///org/gnome/shell/ui/layout.js:901 (3908ac2de920 @ 251)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #1   55f7da57d510 i   resource:///org/gnome/shell/ui/layout.js:862 (3908ac2dea60 @ 401)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #2   55f7da57d460 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:883 (21f252984d80 @ 87)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #3   55f7da57d2d0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:390 (21f252985880 @ 205)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #4   55f7da57d1b0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:634 (21f252985420 @ 625)
Dec 09 15:28:17 lucifer gnome-shell[1904]: Object Meta.BackgroundActor (0x55f7d7a62de0), has been already deallocated — impossible to connect to any signal on it. This might be caused by the object having been destroyed from C code using something such as destroy(), dispose(), or remove() vfuncs.
Dec 09 15:28:17 lucifer gnome-shell[1904]: #5   55f7da57d0f0 i   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/tiling.js:2306 (21f252983240 @ 90)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #6   7ffd5f50c3b0 b   /home/thomas/.local/share/gnome-shell/extensions/paperwm@hedning:matrix.org/utils.js:91 (d75e0d35f10 @ 38)
Dec 09 15:28:17 lucifer gnome-shell[1904]: #7   55f7da57d068 i   resource:///org/gnome/shell/ui/main.js:248 (3908ac2bdce0 @ 12)
Dec 09 15:28:17 lucifer gnome-shell[1904]: JS ERROR: TypeError: this.monitor is null
Dec 09 15:28:17 lucifer gnome-shell[1904]: Window manager warning: META_CURRENT_TIME used to choose focus window; focus window may not be correct.```

[hedning]

A bit slow here.

Don't have tons of time to debug this, but my guess is when the switching monitors with the switch there's a small amount of time where there's no monitors at all (ie. Main.layoutManager.primaryMonitor is nil, or Main.layoutManager.monitors is empty.

This patch might fix the problem:

modified   tiling.js
@@ -1431,6 +1431,10 @@ class Spaces extends Map {
        left with heuristics.
      */
     monitorsChanged() {
+        let primary = Main.layoutManager.primaryMonitor;
+        let monitors = Main.layoutManager.monitors;
+        if (!primary || monitors.length === 0)
+            return;
         this._monitorsChanging = true;
         this.onlyOnPrimary = this.overrideSettings.get_boolean('workspaces-only-on-primary');
 
@@ -1456,8 +1460,6 @@ class Spaces extends Map {
         }
 
         let mru = this.mru();
-        let primary = Main.layoutManager.primaryMonitor;
-        let monitors = Main.layoutManager.monitors;
 
         let finish = () => {
             let activeSpace = this.get(workspaceManager.get_active_workspace());

[jtaala]

Closing as no feedback received and that code area has changed (including now containing a this.monitor null check.

Plus, it's unlikely the issue submitter is still on gnome 3.38 (since Manjaro is rolling release etc.). Please comment though if this is still an issue and we can reopen.