[00:34:43 FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.AssertionError: TRAP
        at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_201]
        at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_201]
        at net.minecraft.server.v1_12_R1.SystemUtils.a(SourceFile:47) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:850) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:423) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:774) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:666) ~[Paper.jar:git-Paper-1612]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_201]
Caused by: java.lang.AssertionError: TRAP
        at net.minecraft.server.v1_12_R1.ItemStack.F(ItemStack.java:117) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.ItemStack.setCount(ItemStack.java:888) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.PlayerInteractManager.a(PlayerInteractManager.java:441) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.PlayerConnection.a(PlayerConnection.java:1050) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.PacketPlayInBlockPlace.a(PacketPlayInBlockPlace.java:26) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.PacketPlayInBlockPlace.a(PacketPlayInBlockPlace.java:5) ~[Paper.jar:git-Paper-1612]
        at net.minecraft.server.v1_12_R1.PlayerConnectionUtils.lambda$ensureMainThread$0(PlayerConnectionUtils.java:14) ~[Paper.jar:git-Paper-1612]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_201]
        at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_201]
        at net.minecraft.server.v1_12_R1.SystemUtils.a(SourceFile:46) ~[Paper.jar:git-Paper-1612]
        ... 5 more
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