crash after casting a spell in arena

It’s the one where the last 3 spells used are cast in your favor. Googled it but the spell is apparently not listed anywhere on the internet.


############################################################################################
FATAL ERROR in
action number 1
of Step Event0
for object obj_battlecontroller:

Push :: Execution Error - Variable Index [0,-1] out of range [1,13] - -5.creatureList(100003,-1)
at gml_Script_bc_CreatureCast
############################################################################################

stack frame is
gml_Script_bc_CreatureCast (line 0)
gml_Script_bc_CreatureCastSpellGem
gml_Script_bc_CreatureCast
gml_Script_bc_Turn
gml_Object_obj_battlecontroller_Step_0

FYI - looks like same crash as:
https://forums.thylacinestudios.com/t/3039