Random crash in a battle not too sure why it hapend

If your game crashes, please copy and paste the full error message below, or post a screenshot of it.


############################################################################################
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_ExecuteEvents
gml_Object_obj_battlecontroller_Step_0

Please describe in as much detail as possible how to reproduce the bug or crash.
I was in a battle and this poped up after i had attacked mid way through a furry swipes and my monster was frozen.

What operating system are you playing the game on? Windows, Mac OS, Android, iOS, or Playstation?
Windows 10

What game version are you playing? You can find the version number on the title screen in the lower left corner.
2.1.5

Hope i have done this right.

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