Consider arguments to team leave properly. Fixes BUKKIT-3994

Two checks to argument length were changed to properly consider if the
sender is a player instead of an off-by-one logical error.

By: Wesley Wolfe <weswolf@aol.com>

paper-api/src/main/java/org/bukkit/command/defaults/ScoreboardCommand.java

@@ -385,13 +385,13 @@ public class ScoreboardCommand extends VanillaCommand {
                     sender.sendMessage("Added " + addedPlayers.size() + " player(s) to team " + team.getName() + ": " + stringCollectionToString(addedPlayers));
                 }
             } else if (args[1].equalsIgnoreCase("leave")) {
-                if ((sender instanceof Player) ? args.length < 2 : args.length < 3) {
+                if (!(sender instanceof Player) && args.length < 3) {
                     sender.sendMessage(ChatColor.RED + "/scoreboard teams leave [player...]");
                     return false;
                 }
                 Set<String> left = new HashSet<String>();
                 Set<String> noTeam = new HashSet<String>();
-                if ((sender instanceof Player) && args.length == 3) {
+                if ((sender instanceof Player) && args.length == 2) {
                     Team team = mainScoreboard.getPlayerTeam((Player) sender);
                     if (team != null) {
                         team.removePlayer((Player) sender);