Add helper method to make direct casts be used

osu.Game.Rulesets.Osu/Skinning/OsuLegacySkinTransformer.cs

@@ -111,7 +111,7 @@ namespace osu.Game.Rulesets.Osu.Skinning
                     {
                         case OsuSkinConfiguration.SliderPathRadius:
                             if (hasHitCircle.Value)
-                                return new BindableFloat(legacy_circle_radius) as Bindable<TValue>;
+                                return SkinUtils.As<TValue>(new BindableFloat(legacy_circle_radius));
 
                             break;
                     }

osu.Game.Tests/Skins/TestSceneSkinConfigurationLookup.cs

@@ -95,6 +95,25 @@ namespace osu.Game.Tests.Skins
             AddAssert("Check combo colours", () => requester.GetConfig<GlobalSkinConfiguration, List<Color4>>(GlobalSkinConfiguration.ComboColours)?.Value?.Count > 0);
         }
 
+        [Test]
+        public void TestWrongColourType()
+        {
+            AddStep("Add config colour", () => { source1.Configuration.CustomColours["Lookup"] = Color4.Red; });
+
+            AddAssert("perform incorrect lookup", () =>
+            {
+                try
+                {
+                    requester.GetConfig<SkinCustomColourLookup, int>(new SkinCustomColourLookup("Lookup"));
+                    return false;
+                }
+                catch
+                {
+                    return true;
+                }
+            });
+        }
+
         public enum LookupType
         {
             Test

osu.Game/Skinning/LegacySkin.cs

@@ -62,16 +62,16 @@ namespace osu.Game.Skinning
                     switch (global)
                     {
                         case GlobalSkinConfiguration.ComboColours:
-                            return new Bindable<List<Color4>>(Configuration.ComboColours) as IBindable<TValue>;
+                            return SkinUtils.As<TValue>(new Bindable<List<Color4>>(Configuration.ComboColours));
                     }
 
                     break;
 
                 case GlobalSkinColour colour:
-                    return getCustomColour(colour.ToString()) as IBindable<TValue>;
+                    return SkinUtils.As<TValue>(getCustomColour(colour.ToString()));
 
                 case SkinCustomColourLookup customColour:
-                    return getCustomColour(customColour.Lookup.ToString()) as IBindable<TValue>;
+                    return SkinUtils.As<TValue>(getCustomColour(customColour.Lookup.ToString()));
 
                 default:
                     try

osu.Game/Skinning/SkinUtils.cs

@@ -0,0 +1,18 @@
+using osu.Framework.Bindables;
+
+namespace osu.Game.Skinning
+{
+    /// <summary>
+    /// Contains helper methods to assist in implementing <see cref="ISkin"/>s.
+    /// </summary>
+    public static class SkinUtils
+    {
+        /// <summary>
+        /// Converts an <see cref="object"/> to a <see cref="Bindable{TValue}"/>. Used for returning configuration values of specific types.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        /// <typeparam name="TValue">The type of value <paramref name="value"/>, and the type of the resulting bindable.</typeparam>
+        /// <returns>The resulting bindable.</returns>
+        public static Bindable<TValue> As<TValue>(object value) => (Bindable<TValue>)value;
+    }
+}