Fix null check issue

BeatTogether.DedicatedServer.Kernel/Managers/LobbyManager.cs

@@ -420,7 +420,7 @@ private bool PlayerMapCheck(IPlayer p)
         {
 	        if(p.BeatmapIdentifier == null) return false;
             //If no map hash then treat as base game map for compat reasons and while waiting for a packet
-            var Passed = p.SelectedBeatmapPacket != null && string.IsNullOrEmpty(p.SelectedBeatmapPacket.levelHash);
+            var Passed = p.SelectedBeatmapPacket != null && !string.IsNullOrEmpty(p.SelectedBeatmapPacket.levelHash);
             //If not passed, then we have difficulties, and if we have the diff we are looking for, then we can check it for requirements.
             if (!Passed && p.SelectedBeatmapPacket!.requirements.TryGetValue((uint)p.BeatmapIdentifier!.Difficulty, out string[]? Requirements))
                 Passed = !(!_configuration.AllowChroma && Requirements.Contains("Chroma")) || !(!_configuration.AllowMappingExtensions && Requirements.Contains("Mapping Extensions")) || !(!_configuration.AllowNoodleExtensions && Requirements.Contains("Noodle Extensions"));