WORLDGUARD-2368 - Reported by paulj1x

1.4.5-R0.1 build #2483
I'm seeing a lot of these errors:
[SEVERE] Could not pass event PlayerInteractEvent to WorldGuard v5.6.5
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:341)
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
at org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:177)
at org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:147)
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:632)
at net.minecraft.server.Packet15Place.handle(SourceFile:58)
at net.minecraft.server.NetworkManager.b(NetworkManager.java:290)
at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:113)
at net.minecraft.server.ServerConnection.b(SourceFile:39)
at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30)
at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:595)
at net.minecraft.server.DedicatedServer.r(DedicatedServer.java:222)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:493)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:426)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:856)
Caused by: java.lang.IllegalArgumentException: Instant potions cannot be extended
at org.apache.commons.lang.Validate.isTrue(Validate.java:157)
at org.bukkit.potion.Potion.setHasExtendedDuration(Potion.java:246)
at org.bukkit.potion.Potion.extend(Potion.java:130)
at org.bukkit.potion.Potion.fromDamage(Potion.java:380)
at org.bukkit.potion.Potion.fromItemStack(Potion.java:389)
at com.sk89q.worldguard.bukkit.WorldGuardPlayerListener.onPlayerInteract(WorldGuardPlayerListener.java:415)
at sun.reflect.GeneratedMethodAccessor78.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:339)
... 16 more