YYC error: "Trying to construct something that isn't a function"

I've been building a game and testing it on VM for a while now, and everything was fine. Today I decided to start testing the game using the YYC.
When using the YYC I get this error at the very start of the game:

############################################
ERROR in
action number 1
of Create Event
for object <undefined>:

Trying to construct something that isn't a function########
gml_GlobalScript_DebugTimer (line 24)

Click to expand...

Here's the DebugTimer script it's referring to...

YYC error: "Trying to construct something that isn't a function"