Fix a NPE when trying to join a non-existing player

Fixes #860

Changelog.txt

@@ -17,6 +17,7 @@ Version 1.4.04-dev
  = Fixed bug where Shake wouldn't damage mobs whose max health was less than 4
  = Fixed bug where the API would fail if the name of a player's current party is requested when the player isn't in one (Thanks @dualspiral!)
  = Fixed bug with retrieving a player's party members
+ = Fixed bug which caused an NPE when trying to join a non-existing player
  ! Updated localization files
  - Removed deprecated functions from API classes.
  - Removed functions for getting the PlayerProfile - using API classes is preferred, but if not the McMMOPlayer should be used instead

src/main/java/com/gmail/nossr50/commands/party/PartyJoinCommand.java

@@ -31,6 +31,9 @@ public class PartyJoinCommand implements CommandExecutor {
                     return true;
                 }
 
+                mcMMOPlayer = UserManager.getPlayer(args[1]);
+                player = mcMMOPlayer.getPlayer();
+
                 String password = getPassword(args);
 
                 // Make sure party passwords match
@@ -63,8 +66,8 @@ public class PartyJoinCommand implements CommandExecutor {
     private boolean canJoinParty(CommandSender sender, String targetName) {
         mcMMOTarget = UserManager.getPlayer(targetName);
 
-        if (CommandUtils.checkPlayerExistence(sender, targetName, mcMMOTarget)) {
+        if (!CommandUtils.checkPlayerExistence(sender, targetName, mcMMOTarget)) {
-            return true;
+            return false;
         }
 
         target = mcMMOTarget.getPlayer();

src/main/java/com/gmail/nossr50/util/commands/CommandUtils.java

@@ -67,17 +67,17 @@ public final class CommandUtils {
 
     public static boolean checkPlayerExistence(CommandSender sender, String playerName, McMMOPlayer mcMMOPlayer) {
         if (mcMMOPlayer != null) {
-            return false;
+            return true;
         }
 
         PlayerProfile playerProfile = new PlayerProfile(playerName, false);
 
         if (unloadedProfile(sender, playerProfile)) {
-            return true;
+            return false;
         }
 
         sender.sendMessage(LocaleLoader.getString("Commands.Offline"));
-        return true;
+        return false;
     }
 
     public static boolean unloadedProfile(CommandSender sender, PlayerProfile profile) {