Unable to set a worldborder in Spigot 1.9.

[11:03:54 INFO]: An unknown error occurred while attempting to perform this command
[11:03:54 WARN]: Unknown CommandBlock failed to handle command
java.lang.NullPointerException
at net.minecraft.server.v1_9_R1.PlayerList.sendAll(PlayerList.java:988) ~[spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at net.minecraft.server.v1_9_R1.PlayerList$1.a(PlayerList.java:258) ~[spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at net.minecraft.server.v1_9_R1.WorldBorder.setSize(WorldBorder.java:167) ~[spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at net.minecraft.server.v1_9_R1.CommandWorldBorder.execute(SourceFile:58) ~[spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at org.bukkit.craftbukkit.v1_9_R1.command.VanillaCommandWrapper.dispatchVanillaCommand(VanillaCommandWrapper.java:108) [spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at org.bukkit.craftbukkit.v1_9_R1.command.VanillaCommandWrapper.execute(VanillaCommandWrapper.java:43) [spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) [spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at org.bukkit.craftbukkit.v1_9_R1.CraftServer.dispatchCommand(CraftServer.java:645) [spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at org.bukkit.craftbukkit.v1_9_R1.CraftServer.dispatchServerCommand(CraftServer.java:631) [spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at net.minecraft.server.v1_9_R1.DedicatedServer.aL(DedicatedServer.java:437) [spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at net.minecraft.server.v1_9_R1.DedicatedServer.D(DedicatedServer.java:401) [spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at net.minecraft.server.v1_9_R1.MinecraftServer.C(MinecraftServer.java:655) [spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at net.minecraft.server.v1_9_R1.MinecraftServer.run(MinecraftServer.java:554) [spigot-1.9.jar:git-Spigot-7d15d07-c194444]
at java.lang.Thread.run(Thread.java:744) [?:1.8.0]