Game Crash On Load Of World

[23:41:37] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 3463ms behind, skipping 69 tick(s)
[23:41:41] [Server thread/ERROR]: Encountered an unexpected exception
h: Exception ticking world
	at net.minecraft.server.MinecraftServer.w(SourceFile:697) ~[minecraft-1.13-pre1-client.jar:?]
	at net.minecraft.server.MinecraftServer.v(SourceFile:626) ~[minecraft-1.13-pre1-client.jar:?]
	at dio.v(SourceFile:156) ~[minecraft-1.13-pre1-client.jar:?]
	at net.minecraft.server.MinecraftServer.run(SourceFile:531) [minecraft-1.13-pre1-client.jar:?]
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_171]
Caused by: java.lang.NullPointerException
	at sm.n_(SourceFile:422) ~[minecraft-1.13-pre1-client.jar:?]
	at sm.i_(SourceFile:220) ~[minecraft-1.13-pre1-client.jar:?]
	at net.minecraft.server.MinecraftServer.w(SourceFile:693) ~[minecraft-1.13-pre1-client.jar:?]
	... 4 more