Object St.BoxLayout has been already deallocated

[p91paul]

On gnome shell 3.28 (arch linux) I get this in journalctl output:

gnome-shell[854]: Object St.BoxLayout (0x5638a46de570), has been already deallocated - impossible to access to it. This might be caused by the fact that the object has been destroyed from C code using something such as destroy(), dispose(), or remove() vfuncs
org.gnome.Shell.desktop[854]: == Stack trace for context 0x5638a0daf050 ==
org.gnome.Shell.desktop[854]: #0 0x7ffda3a9c780 b   /home/paolo/.local/share/gnome-shell/extensions/TaskBar@zpydr/extension.js:2626 (0x7f77f40c8670 @ 2626)
org.gnome.Shell.desktop[854]: #1 0x7ffda3a9c7c0 I   /home/paolo/.local/share/gnome-shell/extensions/TaskBar@zpydr/extension.js:2282 (0x7f77f40c6f78 @ 20)
org.gnome.Shell.desktop[854]: #2 0x7ffda3a9c820 I   self-hosted:251 (0x7f78146c4ab0 @ 223)
org.gnome.Shell.desktop[854]: #3 0x7ffda3a9c8e0 b   /home/paolo/.local/share/gnome-shell/extensions/TaskBar@zpydr/extension.js:2279 (0x7f77f40c6ef0 @ 51)
org.gnome.Shell.desktop[854]: #4 0x7ffda3a9c9d0 b   /home/paolo/.local/share/gnome-shell/extensions/TaskBar@zpydr/windows.js:111 (0x7f77f40e6340 @ 224)
org.gnome.Shell.desktop[854]: #5 0x7ffda3a9ca60 I   self-hosted:918 (0x7f78146ebf78 @ 394)

It seems to be linked to some freezes I'm getting in gnome-shell every few minutes (shell locks for some seconds, and this message appears in logs). I'm trying to run without this extension to see if it is actually the cause.