Frostbite

I'm currently in Blacksteeple Castle, and I'm supposed to be looking for a purple book in the library. However, when I try walking through the door, I get an error and my game crashes. This is what the error says: "Script 'Game_Event_' line 164: ArgumentError occured. comparison of String with 21 failed Not sure what to do, if someone could help it'd be appreciated. Save file in case you need it game.rxdata