Throw rather than ignore on invalid control point addition

osu.Game/Beatmaps/ControlPoints/ControlPointInfo.cs

@@ -276,6 +276,9 @@ namespace osu.Game.Beatmaps.ControlPoints
                 case EffectControlPoint typed:
                     effectPoints.Add(typed);
                     break;
+
+                default:
+                    throw new ArgumentException($"A control point of unexpected type {controlPoint.GetType()} was added to this {nameof(ControlPointInfo)}");
             }
         }
 

osu.Game/Beatmaps/Legacy/LegacyControlPointInfo.cs

@@ -73,14 +73,16 @@ namespace osu.Game.Beatmaps.Legacy
             {
                 case SampleControlPoint typed:
                     samplePoints.Add(typed);
-                    break;
+                    return;
 
                 case DifficultyControlPoint typed:
                     difficultyPoints.Add(typed);
+                    return;
+
+                default:
+                    base.GroupItemAdded(controlPoint);
                     break;
             }
-
-            base.GroupItemAdded(controlPoint);
         }
 
         protected override void GroupItemRemoved(ControlPoint controlPoint)