Parse error when trying to extend script with declared class_name

[aesereht]

Maybe related with #338

When trying to extend script with it produce errors. The example above was when trying to extend the _ready() method .

In case of just adding the code even without execution it will also produce error

func test():
	print("test")

where the script that produce error is not connected to extended script
MultiplayerloadoutStage.gd was the extended script while GameWorld.availableTechSlots.duplicate() produced error
GameWorld is a singleton

MultiplayerloadoutStage.gd first lines

extends Stage
class_name MultiplayerLoadoutStage
...

[ZackeryRSmith]

Duplicate of #345