code bug

Did you start another copy of Minecraft and attempt to load the same world?

...

[18:58:40] [Server thread/INFO]: [@: Teleported Clone to -793.6999999880791,30.0,-280.17620929784556]
[18:58:53] [Server thread/INFO]: Starting integrated minecraft server version 14w08a
[18:58:53] [Server thread/INFO]: Generating keypair
[18:58:53] [Server thread/ERROR]: Couldn't process command: 'testfor @e[-793,31,-311,1]'
java.lang.NullPointerException
	at net.minecraft.server.MinecraftServer.a(SourceFile:1153) ~[14w08a.jar:?]
	at x.a(SourceFile:169) ~[14w08a.jar:?]
	at x.b(SourceFile:155) ~[14w08a.jar:?]
	at cq.b(SourceFile:34) ~[14w08a.jar:?]
	at z.a(SourceFile:54) [14w08a.jar:?]
	at aim.a(SourceFile:91) [14w08a.jar:?]
	at ame.b(SourceFile:50) [14w08a.jar:?]
	at ob.a(SourceFile:445) [14w08a.jar:?]
	at ob.c(SourceFile:159) [14w08a.jar:?]
	at net.minecraft.server.MinecraftServer.w(SourceFile:529) [14w08a.jar:?]
	at net.minecraft.server.MinecraftServer.v(SourceFile:471) [14w08a.jar:?]
	at cby.v(SourceFile:128) [14w08a.jar:?]
	at net.minecraft.server.MinecraftServer.run(SourceFile:387) [14w08a.jar:?]
	at mr.run(SourceFile:657) [14w08a.jar:?]

...

[18:58:53] [Server thread/INFO]: sdk345 lost connection: TextComponent{text='Disconnected', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}
[18:58:53] [Server thread/INFO]: sdk345 left the game
[18:58:53] [Server thread/INFO]: Stopping singleplayer server as player logged out
[18:58:53] [Server thread/ERROR]: Couldn't save chunk; already in use by another instance of Minecraft?
ajf: The save is being accessed from another location, aborting
	at bbo.c(SourceFile:64) ~[14w08a.jar:?]
	at aja.H(SourceFile:2540) ~[14w08a.jar:?]
	at atc.a(SourceFile:93) ~[14w08a.jar:?]
	at oa.b(SourceFile:161) [14w08a.jar:?]
	at oa.d(SourceFile:220) [14w08a.jar:?]
	at ob.c(SourceFile:145) [14w08a.jar:?]
	at net.minecraft.server.MinecraftServer.w(SourceFile:529) [14w08a.jar:?]
	at net.minecraft.server.MinecraftServer.v(SourceFile:471) [14w08a.jar:?]
	at cby.v(SourceFile:128) [14w08a.jar:?]
	at net.minecraft.server.MinecraftServer.run(SourceFile:387) [14w08a.jar:?]
	at mr.run(SourceFile:657) [14w08a.jar:?]
[18:58:53] [Server thread/ERROR]: Couldn't save chunk; already in use by another instance of Minecraft?

I am getting this bug on the latest snapshot, 14w30b. I had it set to 32 chunk render distance and when I tried moving to the edge of the render distance I had when I spawned, it refused to load more chunks. I could even move down into the space that should have been occupied without being hindered. Will attach screenshot.

The log suddenly started spewing the "being accessed from another location" error at me when that was happening. I had to kill both the Minecraft and Launcher processes to stop it. I will also attach this log.

Uploaded "latest.log" at 11:47, 23 July 2014 (MDT), from snapshot 14w30b.

Uploaded "2014-07-23_11.41.30.png" at 11:49, 23 July 2014 (MDT), from snapshot 14w30b.

@unknown: Your issue has nothing to do with this ticket, see MC-63359

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.

Ticket resolved as incomplete, because no answer in a reasonable amount of time (1+ year), if it still happens, please update the ticket.