Merge pull request #16627 from peppy/fix-ruleset-import-failure

Fix realm migration failures with presence of databased EF rulesets that don't exist on disk

osu.Game/Database/EFToRealmMigrator.cs

@@ -286,6 +286,7 @@ namespace osu.Game.Database
 
                 var transaction = r.BeginWrite();
                 int written = 0;
+                int missing = 0;
 
                 try
                 {
@@ -300,6 +301,13 @@ namespace osu.Game.Database
 
                         var beatmap = r.All<BeatmapInfo>().First(b => b.Hash == score.BeatmapInfo.Hash);
                         var ruleset = r.Find<RulesetInfo>(score.Ruleset.ShortName);
+
+                        if (ruleset == null)
+                        {
+                            log($"Skipping {++missing} scores with missing ruleset");
+                            continue;
+                        }
+
                         var user = new RealmUser
                         {
                             OnlineID = score.User.OnlineID,

osu.Game/Rulesets/EFRulesetInfo.cs

@@ -28,21 +28,15 @@ namespace osu.Game.Rulesets
         public Ruleset CreateInstance()
         {
             if (!Available)
-                throw new RulesetLoadException(@"Ruleset not available");
+                return null;
 
             var type = Type.GetType(InstantiationInfo);
 
             if (type == null)
-                throw new RulesetLoadException(@"Type lookup failure");
+                return null;
 
             var ruleset = Activator.CreateInstance(type) as Ruleset;
 
-            if (ruleset == null)
-                throw new RulesetLoadException(@"Instantiation failure");
-
-            // overwrite the pre-populated RulesetInfo with a potentially database attached copy.
-            // ruleset.RulesetInfo = this;
-
             return ruleset;
         }