Crash: java.lang.NullPointerException

I can't even log into my own server any more because of this crash! Someone plz help me! (The crash is the attached file)

Excerpt:

java.lang.NullPointerException
at bkv.a(SourceFile:303)
at ays.o(SourceFile:1278)
at ays.ab(SourceFile:755)
at ays.e(SourceFile:706)
at net.minecraft.client.main.Main.main(SourceFile:103)