Crash when deleting token inside a chunk such that the resulting chunk coincides with another chunk

[kayaulai]

1. Create a chunk, I [am very] happy.
2. Create a chunk with one more word on the right, e.g. I [am very happy].
3. Delete the word in the first chunk but not the second.

An error should result.

---

############################################################################################
ERROR in action number 1
of Draw Event for object obj_chain:
ds_map_find_value argument 1 incorrect type (undefined) expecting a ds_map
at gml_Script_scr_drawChunks
############################################################################################
gml_Script_scr_drawChunks (line -1)
gml_Object_obj_chain_Draw_0

The error should instead be caught and an popup message shown.