Game randomly broke

I added a new enemy, and then when I went to restart the game, the cutscene sprites wont appear, it always errored when the cutscene ended, and it just got worse and worse. Can somebody check it out? Thanks.

The bug probably is here, where PlasticThrower referrence have not create yet.

Add if(PlasticThrower) as following. Then bug 's gone, in my test

Thank you so much I needed this for a school project, and I am still quite new to making games.