The mod Toolbars (2.38.2) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event toolbars-mod::on_gui_click (ID 1)
toolbars-mod/src/gui/toolbar/Toolbar.lua:45: attempt to index a nil value
stack traceback:
toolbars-mod/src/gui/toolbar/Toolbar.lua:45: in function 'toggle'
toolbars-mod/src/gui/toolbar/header/ToolbarHeader.lua:78: in function 'onDoubleLeftClick'
toolbars-mod/src/gui/Component.lua:155: in function 'propagateOnClick'
toolbars-mod/src/gui/Component.lua:164: in function 'propagateOnClick'
toolbars-mod/src/gui/Gui.lua:88: in function 'handleClick'
toolbars-mod/control/gui.lua:38: in function <toolbars-mod/control/gui.lua:35>

Does it happen all the time or only for a specific old toolbar?

Edit:
It looks like you double clicked trash icon, I will try to reproduce that and fix it. Double click on a header also let's you fold toolbar but in this case it was already deleted.

Fixed in 2.38.3.