Fix thread-safety issues with /rtp

Author: anhcraft

src/main/java/com/fibermc/essentialcommands/commands/RandomTeleportCommand.java

@@ -1,6 +1,7 @@
 package com.fibermc.essentialcommands.commands;
 
 import java.util.Random;
+import java.util.concurrent.CompletableFuture;
 
 import com.fibermc.essentialcommands.EssentialCommands;
 import com.fibermc.essentialcommands.ManagerLocator;
@@ -19,6 +20,7 @@
 import net.minecraft.block.BlockState;
 import net.minecraft.block.Material;
 import net.minecraft.command.CommandException;
+import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.command.ServerCommandSource;
 import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.server.world.ServerWorld;
@@ -78,15 +80,14 @@ public int run(CommandContext<ServerCommandSource> context) throws CommandSyntax
             playerData.setTimeUsedRtp(curServerTickTime);
         }
 
-        new Thread("RTP Location Calculator Thread") {
-            public void run() {
-                try {
-                    exec(context.getSource(), world);
-                } catch (CommandSyntaxException e) {
-                    e.printStackTrace();
-                }
+        CompletableFuture.runAsync(() -> {
+            try {
+                exec(context.getSource(), world);
+            } catch (CommandSyntaxException e) {
+                e.printStackTrace();
             }
-        }.start();
+        });
+
         return 1;
     }
 
@@ -156,11 +157,11 @@ private static int exec(ServerPlayerEntity player, ServerWorld world, MinecraftL
         }
 
         // Teleport the player
-        PlayerTeleporter.requestTeleport(
+        world.getServer().executeSync(() -> PlayerTeleporter.requestTeleport(
             player,
             new MinecraftLocation(world.getRegistryKey(), new_x, new_y, new_z, 0, 0),
             ecText.getText("cmd.rtp.location_name")
-        );
+        ));
 
         return 1;
     }