Reduce error count.

osu.Game/Overlays/Mods/ModSelectOverlay.cs

@@ -167,7 +167,7 @@ namespace osu.Game.Overlays.Mods
             // 1.05x
             // 1.20x
 
-            multiplierLabel.Text = string.Format("{0:N2}x", multiplier);
+            multiplierLabel.Text = $"{multiplier:N2}x";
             string rankedString = ranked ? "Ranked" : "Unranked";
             rankedLabel.Text = $@"{rankedString}, Score Multiplier: ";
 

osu.Game/Overlays/Options/OptionDropDown.cs

@@ -39,7 +39,7 @@ namespace osu.Game.Overlays.Options
                 bindable.ValueChanged += bindable_ValueChanged;
                 bindable_ValueChanged(null, null);
 
-                if (bindable?.Disabled ?? true)
+                if ((bool)bindable?.Disabled)
                     Alpha = 0.3f;
             }
         }

osu.Game/Overlays/Toolbar/ToolbarModeSelector.cs

@@ -64,11 +64,8 @@ namespace osu.Game.Overlays.Toolbar
                 }
             };
 
-            int amountButtons = 0;
             foreach (PlayMode m in Enum.GetValues(typeof(PlayMode)))
             {
-                ++amountButtons;
-
                 var localMode = m;
                 modeButtons.Add(new ToolbarModeButton
                 {

osu.Game/Overlays/Toolbar/ToolbarUserButton.cs

@@ -94,11 +94,7 @@ namespace osu.Game.Overlays.Toolbar
 
                     userId = value;
 
-                    Sprite newSprite;
-                    if (userId > 1)
-                        newSprite = new OnlineSprite($@"https://a.ppy.sh/{userId}");
-                    else
-                        newSprite = new Sprite { Texture = guestTexture };
+                    var newSprite = userId > 1 ? new OnlineSprite($@"https://a.ppy.sh/{userId}") : new Sprite { Texture = guestTexture };
 
                     newSprite.FillMode = FillMode.Fit;