I was playing minecraft and I accidentally held shift when pressing F3 and it crashed. To verify that this was the problem, I tried the same thing, and it crashed. Here's the error in the console:
Unreported exception thrown!
java.lang.ArrayIndexOutOfBoundsException: -1
at java.util.ArrayList.elementData(ArrayList.java:418)
at java.util.ArrayList.remove(ArrayList.java:495)
at qn.b(SourceFile:70)
at bgu.aw(SourceFile:989)
at bgu.a(SourceFile:399)
at net.minecraft.client.main.Main.main(SourceFile:123)