java.lang.IllegalStateException: Asynchronous entity add!

[12:03:11 WARN]:        at org.spigotmc.AsyncCatcher.catchOp(AsyncCatcher.java:14)

[12:03:11 WARN]:        at net.minecraft.server.v1_11_R1.World.addEntity(World.java:1013)

[12:03:11 WARN]:        at net.minecraft.server.v1_11_R1.WorldServer.addEntity(WorldServer.java:1065)

[12:03:11 WARN]:        at org.bukkit.craftbukkit.v1_11_R1.CraftWorld.addEntity(CraftWorld.java:1203)

[12:03:11 WARN]:        at org.bukkit.craftbukkit.v1_11_R1.CraftWorld.spawn(CraftWorld.java:1210)

[12:03:11 WARN]:        at org.bukkit.craftbukkit.v1_11_R1.CraftWorld.spawn(CraftWorld.java:854)

[12:03:11 WARN]:        at de.league.phase.LobbyPhase$1.run(LobbyPhase.java:14)

[12:03:11 WARN]:        at java.base/java.util.TimerThread.mainLoop(Timer.java:556)

[12:03:11 WARN]:        at java.base/java.util.TimerThread.run(Timer.java:506)