Fix player addition logic in match handling

Prevent adding a player to matchPlayers if userIndex is not found.

src/routes/tournaments/[tournamentguid]/matches/[matchGuid]/+page.svelte

@@ -821,7 +821,7 @@
                 ...matchPlayers.slice(userIndex + 1)
             ];
         } else {
-            matchPlayers = [...matchPlayers, params[0]];
+            return;
         }
     }
 
@@ -1717,4 +1717,4 @@
             gap: 0.75rem;
         }
     }
-</style>
+</style>