When joining a server and switching to "Spectator" mode anyone on the server before you with a different vision setting (night vs normal) than you, you can't spectate without crashing.
Video of the bug in action. If you change vision modes after online it will fix the issue.
http://youtu.be/sCXBWSfMFJw
Description: Unexpected error
java.lang.NullPointerException: Unexpected error
at bpq.a(SourceFile:862)
at bpq.j(SourceFile:1637)
at bpq.a(SourceFile:1063)
at bpq.b(SourceFile:935)
at bcf.ag(SourceFile:803)
at bcf.f(SourceFile:730)
at net.minecraft.client.main.Main.main(SourceFile:154)
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases. If this has been done, we can reopen the issue.
Keep in mind that the "Resolved"-Status on this ticket just means "Answered", and that we are waiting for further information on whether this issue still exists or not. We will reopen it as soon as the requested information has been delivered.