Server crash - Ticking world entities

18w30a server crashes with "Stack Overflow" message. Crash log indicates an "out of bounds exception" while ticking world entities. This is just by wandering around in my base. 

(18w30a) [^crash-2018-07-25_12.23.44-server.txt]

Description: Exception ticking world entities

java.lang.ArrayIndexOutOfBoundsException: -1
	at it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet.fixPointers(ObjectLinkedOpenHashSet.java:851)
	at it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet.shiftKeys(ObjectLinkedOpenHashSet.java:479)
	at it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet.removeEntry(ObjectLinkedOpenHashSet.java:486)
	at it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet.rem(ObjectLinkedOpenHashSet.java:514)
	at it.unimi.dsi.fastutil.objects.AbstractObjectCollection.remove(AbstractObjectCollection.java:145)
	at it.unimi.dsi.fastutil.objects.AbstractObjectCollection.removeAll(AbstractObjectCollection.java:210)
	at axu.l(SourceFile:1068)
	at tc.l(SourceFile:493)
	at net.minecraft.server.MinecraftServer.b(SourceFile:736)
	at sn.b(SourceFile:358)
	at net.minecraft.server.MinecraftServer.a(SourceFile:661)
	at net.minecraft.server.MinecraftServer.run(SourceFile:564)
	at java.lang.Thread.run(Unknown Source)