fixed crash

Author: ArkadySK

GbxMapBrowser/MapInfo.cs

@@ -73,7 +73,11 @@ public MapInfo(string fullnamepath, bool basicInfoOnly)
                     ? enviImagePath
                     : new Uri(Environment.CurrentDirectory + "\\Data\\Environments\\Unknown.png");
 
-                bool isRace = challenge.Mode == CGameCtnChallenge.PlayMode.Race || challenge.MapType.EndsWith("Race");
+                MapType = string.IsNullOrEmpty(challenge.ChallengeParameters?.MapType)
+                    ? challenge.Mode.ToString()
+                    : challenge.ChallengeParameters.MapType;
+
+                bool isRace = challenge.Mode == CGameCtnChallenge.PlayMode.Race || MapType.EndsWith("Race");
 
                 ObjectiveAuthor = !string.IsNullOrEmpty(challenge.ObjectiveTextAuthor) && !isRace
                     ? challenge.ObjectiveTextAuthor
@@ -97,10 +101,6 @@ public MapInfo(string fullnamepath, bool basicInfoOnly)
 
                 CopperPrice = challenge.Cost.ToString();
 
-                MapType = string.IsNullOrEmpty(challenge.ChallengeParameters.MapType)
-                    ? challenge.Mode.ToString()
-                    : challenge.ChallengeParameters.MapType;
-
                 if (challenge.Thumbnail == null)
                 {
                     MapThumbnail = new BitmapImage(new Uri(Environment.CurrentDirectory + "\\Data\\UIIcons\\NoThumbnail.png"));