When I use left or right arrow (to change tab) when there is no tabs (e.g. after assimilation) the game crash with this error:

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FATAL ERROR in
action number 1
of Other Event: User Defined 10
for object scroller:

local variable _id(100002, -2147483648) not set before reading it.
at gml_Object_scroller_Other_20
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stack frame is
gml_Object_scroller_Other_20 (line -1)
called from - gml_Object_scroller_KeyPress_39 (line -1) - <unknown source line>