Hey, am running latest release of PaperMC with WB Beta 1.9.10. After "wb world fill 20 208 true" command i get this error. The command works but i don't want to get any of my chunks corrupted or something. Thanks!

[Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH - git-Paper-221 (MC: 1.14.4) ---
[15:49:04] [Paper Watchdog Thread/ERROR]: The server has not responded for 10 seconds! Creating thread dump
[15:49:04] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:04] [Paper Watchdog Thread/ERROR]: Server thread dump (Look for plugins here before reporting to Paper!):
[15:49:04] [Paper Watchdog Thread/ERROR]: The server is waiting on these chunks: [[( -227,52) in 'world']]
[15:49:04] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:04] [Paper Watchdog Thread/ERROR]: Current Thread: Server thread
[15:49:04] [Paper Watchdog Thread/ERROR]: PID: 23 | Suspended: false | Native: false | State: TIMED_WAITING
[15:49:04] [Paper Watchdog Thread/ERROR]: Stack:
[15:49:04] [Paper Watchdog Thread/ERROR]: sun.misc.Unsafe.park(Native Method)
[15:49:04] [Paper Watchdog Thread/ERROR]: java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IAsyncTaskHandler.bi(IAsyncTaskHandler.java:131)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:120)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:285)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.World.getChunkAt(World.java:373)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IWorldReader.getChunkAt(IWorldReader.java:80)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.World.getChunkAt(World.java:334)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.WorldServer.setForceLoaded(WorldServer.java:1803)
[15:49:04] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.CraftWorld.setChunkForceLoaded(CraftWorld.java:679)
[15:49:04] [Paper Watchdog Thread/ERROR]: com.wimbli.WorldBorder.WorldFillTask.run(WorldFillTask.java:318)
[15:49:04] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftTask.run(CraftTask.java:84)
[15:49:04] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:452)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.b(MinecraftServer.java:1171)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.DedicatedServer.b(DedicatedServer.java:417)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.a(MinecraftServer.java:1098)
[15:49:04] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.run(MinecraftServer.java:925)
[15:49:04] [Paper Watchdog Thread/ERROR]: java.lang.Thread.run(Thread.java:748)
[15:49:04] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:04] [Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH ---
[15:49:04] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:09] [Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH - git-Paper-221 (MC: 1.14.4) ---
[15:49:09] [Paper Watchdog Thread/ERROR]: The server has not responded for 15 seconds! Creating thread dump
[15:49:09] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:09] [Paper Watchdog Thread/ERROR]: Server thread dump (Look for plugins here before reporting to Paper!):
[15:49:09] [Paper Watchdog Thread/ERROR]: The server is waiting on these chunks: [[( -227,52) in 'world']]
[15:49:09] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:09] [Paper Watchdog Thread/ERROR]: Current Thread: Server thread
[15:49:09] [Paper Watchdog Thread/ERROR]: PID: 23 | Suspended: false | Native: false | State: TIMED_WAITING
[15:49:09] [Paper Watchdog Thread/ERROR]: Stack:
[15:49:09] [Paper Watchdog Thread/ERROR]: sun.misc.Unsafe.park(Native Method)
[15:49:09] [Paper Watchdog Thread/ERROR]: java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IAsyncTaskHandler.bi(IAsyncTaskHandler.java:131)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:120)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:285)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.World.getChunkAt(World.java:373)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IWorldReader.getChunkAt(IWorldReader.java:80)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.World.getChunkAt(World.java:334)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.WorldServer.setForceLoaded(WorldServer.java:1803)
[15:49:09] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.CraftWorld.setChunkForceLoaded(CraftWorld.java:679)
[15:49:09] [Paper Watchdog Thread/ERROR]: com.wimbli.WorldBorder.WorldFillTask.run(WorldFillTask.java:318)
[15:49:09] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftTask.run(CraftTask.java:84)
[15:49:09] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:452)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.b(MinecraftServer.java:1171)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.DedicatedServer.b(DedicatedServer.java:417)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.a(MinecraftServer.java:1098)
[15:49:09] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.run(MinecraftServer.java:925)
[15:49:09] [Paper Watchdog Thread/ERROR]: java.lang.Thread.run(Thread.java:748)
[15:49:09] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:09] [Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH ---
[15:49:09] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:14] [Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH - git-Paper-221 (MC: 1.14.4) ---
[15:49:14] [Paper Watchdog Thread/ERROR]: The server has not responded for 20 seconds! Creating thread dump
[15:49:14] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:14] [Paper Watchdog Thread/ERROR]: Server thread dump (Look for plugins here before reporting to Paper!):
[15:49:14] [Paper Watchdog Thread/ERROR]: The server is waiting on these chunks: [[( -227,52) in 'world']]
[15:49:14] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:14] [Paper Watchdog Thread/ERROR]: Current Thread: Server thread
[15:49:14] [Paper Watchdog Thread/ERROR]: PID: 23 | Suspended: false | Native: false | State: TIMED_WAITING
[15:49:14] [Paper Watchdog Thread/ERROR]: Stack:
[15:49:14] [Paper Watchdog Thread/ERROR]: sun.misc.Unsafe.park(Native Method)
[15:49:14] [Paper Watchdog Thread/ERROR]: java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IAsyncTaskHandler.bi(IAsyncTaskHandler.java:131)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:120)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:285)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.World.getChunkAt(World.java:373)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IWorldReader.getChunkAt(IWorldReader.java:80)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.World.getChunkAt(World.java:334)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.WorldServer.setForceLoaded(WorldServer.java:1803)
[15:49:14] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.CraftWorld.setChunkForceLoaded(CraftWorld.java:679)
[15:49:14] [Paper Watchdog Thread/ERROR]: com.wimbli.WorldBorder.WorldFillTask.run(WorldFillTask.java:318)
[15:49:14] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftTask.run(CraftTask.java:84)
[15:49:14] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:452)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.b(MinecraftServer.java:1171)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.DedicatedServer.b(DedicatedServer.java:417)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.a(MinecraftServer.java:1098)
[15:49:14] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.run(MinecraftServer.java:925)
[15:49:14] [Paper Watchdog Thread/ERROR]: java.lang.Thread.run(Thread.java:748)
[15:49:14] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:14] [Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH ---
[15:49:14] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:19] [Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH - git-Paper-221 (MC: 1.14.4) ---
[15:49:19] [Paper Watchdog Thread/ERROR]: The server has not responded for 25 seconds! Creating thread dump
[15:49:19] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:19] [Paper Watchdog Thread/ERROR]: Server thread dump (Look for plugins here before reporting to Paper!):
[15:49:19] [Paper Watchdog Thread/ERROR]: The server is waiting on these chunks: [[( -227,51) in 'world']]
[15:49:19] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:19] [Paper Watchdog Thread/ERROR]: Current Thread: Server thread
[15:49:19] [Paper Watchdog Thread/ERROR]: PID: 23 | Suspended: false | Native: false | State: TIMED_WAITING
[15:49:19] [Paper Watchdog Thread/ERROR]: Stack:
[15:49:19] [Paper Watchdog Thread/ERROR]: sun.misc.Unsafe.park(Native Method)
[15:49:19] [Paper Watchdog Thread/ERROR]: java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IAsyncTaskHandler.bi(IAsyncTaskHandler.java:131)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:120)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:285)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.World.getChunkAt(World.java:373)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.IWorldReader.getChunkAt(IWorldReader.java:80)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.World.getChunkAt(World.java:334)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.WorldServer.setForceLoaded(WorldServer.java:1803)
[15:49:19] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.CraftWorld.setChunkForceLoaded(CraftWorld.java:679)
[15:49:19] [Paper Watchdog Thread/ERROR]: com.wimbli.WorldBorder.WorldFillTask.run(WorldFillTask.java:326)
[15:49:19] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftTask.run(CraftTask.java:84)
[15:49:19] [Paper Watchdog Thread/ERROR]: org.bukkit.craftbukkit.v1_14_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:452)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.b(MinecraftServer.java:1171)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.DedicatedServer.b(DedicatedServer.java:417)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.a(MinecraftServer.java:1098)
[15:49:19] [Paper Watchdog Thread/ERROR]: net.minecraft.server.v1_14_R1.MinecraftServer.run(MinecraftServer.java:925)
[15:49:19] [Paper Watchdog Thread/ERROR]: java.lang.Thread.run(Thread.java:748)
[15:49:19] [Paper Watchdog Thread/ERROR]: ------------------------------
[15:49:19] [Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH ---
[15:49:19] [Paper Watchdog Thread/ERROR]: ------------------------------

Hi, I encountered this issue too. Turns out it's been fixed by Paper update #221. It's referenced here PaperMC/Paper#2647