shadow-single-player-owner-fix: (#1687)

* shadow-single-player-owner-fix:
* Disallow shadowing a single player server owner. Fixes #1442

* shadow-single-player-owner-fix:
* Remove some redundant calls

src/main/java/carpet/commands/PlayerCommand.java

@@ -365,6 +365,10 @@ public class PlayerCommand
             Messenger.m(context.getSource(), "r Cannot shadow fake players");
             return 0;
         }
+        if (player.getServer().isSingleplayerOwner(player.getGameProfile())) {
+            Messenger.m(context.getSource(), "r Cannot shadow single-player server owner");
+            return 0;
+        }
         ServerPlayer sendingPlayer = null;
         try
         {