Change your OPEN script into an ENTER and your script should at least work. Because I don't think you want to morph the entire map into a pig. (The OPEN script means that the activator is literally the opening of the map. By using an ENTER script, your activator then becomes the player(s) who actually enter the map.)
What should happen would be ZDoom aborting with an error message along the lines of "Script 1 has performed an illegal operation and needs to be shutdown."