I looked into this, the line that causes the issue is line 24 of ev_batville_veggiscene:
gml_Script_ev_batville_veggiescene (line 24) - csc_q(prompt_add_alt("Like chicken, I guess...",0010))
The underlying problem is that csc_q tries to deactivate the object that is returned, but prompt_add_alt doesn't return an object. I think modifying it like this is all you need to fix the issue:
(in previous versions of Game Maker scripts would return 0 if no return value was specified, which is a valid ID for instance_deactivate functions even if it's never actually used as an instance ID)