fixed missing client side server references. fixes #311

src/main/java/carpet/commands/SpawnCommand.java

@@ -16,6 +16,7 @@ import net.minecraft.command.arguments.DimensionArgumentType;
 import net.minecraft.entity.EntityCategory;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.server.command.ServerCommandSource;
+import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.util.DyeColor;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.dimension.DimensionType;
@@ -195,7 +196,7 @@ public class SpawnCommand
         TickSpeed.tickrate_advance(null, 0, null, null);
         // tick warp given player
         ServerCommandSource csource = null;
-        PlayerEntity player = null;
+        ServerPlayerEntity player = null;
         try
         {
             player = source.getPlayer();