diff --git a/PerformanceCalculatorGUI/APIManager.cs b/PerformanceCalculatorGUI/APIManager.cs
index e2ec077..65aec67 100644
--- a/PerformanceCalculatorGUI/APIManager.cs
+++ b/PerformanceCalculatorGUI/APIManager.cs
@@ -1,6 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System.Diagnostics;
 using System.Globalization;
 using System.Net.Http;
 using System.Threading.Tasks;
@@ -33,7 +34,10 @@ namespace PerformanceCalculatorGUI
         public async Task<T> GetJsonFromApi<T>(string request)
         {
             if (token == null)
+            {
                 await getAccessToken();
+                Debug.Assert(token != null);
+            }
 
             using var req = new JsonWebRequest<T>($"{ENDPOINT_CONFIGURATION.APIEndpointUrl}/api/v2/{request}");
             req.AddHeader("x-api-version", api_version.ToString(CultureInfo.InvariantCulture));
diff --git a/PerformanceCalculatorGUI/Components/ScreenSelectionButton.cs b/PerformanceCalculatorGUI/Components/ScreenSelectionButton.cs
index 8319287..7076605 100644
--- a/PerformanceCalculatorGUI/Components/ScreenSelectionButton.cs
+++ b/PerformanceCalculatorGUI/Components/ScreenSelectionButton.cs
@@ -2,24 +2,12 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using osu.Framework.Graphics.Sprites;
-using osu.Framework.Localisation;
-using osu.Game.Beatmaps.Drawables.Cards;
 using osu.Game.Input.Bindings;
 using osu.Game.Overlays.Toolbar;
 using osuTK;
 
 namespace PerformanceCalculatorGUI.Components
 {
-    public class ScreenSelectionButtonIcon : IconPill
-    {
-        public ScreenSelectionButtonIcon(IconUsage? icon = null)
-            : base(icon ?? FontAwesome.Solid.List)
-        {
-        }
-
-        public override LocalisableString TooltipText => string.Empty;
-    }
-
     internal class ScreenSelectionButton : ToolbarButton
     {
         public ScreenSelectionButton(string title, IconUsage? icon = null, GlobalAction? hotkey = null)
diff --git a/PerformanceCalculatorGUI/Components/ScreenSelectionButtonIcon.cs b/PerformanceCalculatorGUI/Components/ScreenSelectionButtonIcon.cs
new file mode 100644
index 0000000..8032a9e
--- /dev/null
+++ b/PerformanceCalculatorGUI/Components/ScreenSelectionButtonIcon.cs
@@ -0,0 +1,18 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Localisation;
+using osu.Game.Beatmaps.Drawables.Cards;
+
+namespace PerformanceCalculatorGUI.Components;
+
+public class ScreenSelectionButtonIcon : IconPill
+{
+    public ScreenSelectionButtonIcon(IconUsage? icon = null)
+        : base(icon ?? FontAwesome.Solid.List)
+    {
+    }
+
+    public override LocalisableString TooltipText => string.Empty;
+}
diff --git a/PerformanceCalculatorGUI/ExtendedDifficultyCalculator.cs b/PerformanceCalculatorGUI/ExtendedDifficultyCalculator.cs
index dcb3627..1931ebe 100644
--- a/PerformanceCalculatorGUI/ExtendedDifficultyCalculator.cs
+++ b/PerformanceCalculatorGUI/ExtendedDifficultyCalculator.cs
@@ -15,12 +15,6 @@ using osu.Game.Rulesets.Taiko.Difficulty;
 
 namespace PerformanceCalculatorGUI
 {
-    public interface IExtendedDifficultyCalculator
-    {
-        Skill[] GetSkills();
-        DifficultyHitObject[] GetDifficultyHitObjects(IBeatmap beatmap, double clockRate);
-    }
-
     public class ExtendedOsuDifficultyCalculator : OsuDifficultyCalculator, IExtendedDifficultyCalculator
     {
         private Skill[] skills;
diff --git a/PerformanceCalculatorGUI/IExtendedDifficultyCalculator.cs b/PerformanceCalculatorGUI/IExtendedDifficultyCalculator.cs
new file mode 100644
index 0000000..5671a0b
--- /dev/null
+++ b/PerformanceCalculatorGUI/IExtendedDifficultyCalculator.cs
@@ -0,0 +1,14 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Game.Beatmaps;
+using osu.Game.Rulesets.Difficulty.Preprocessing;
+using osu.Game.Rulesets.Difficulty.Skills;
+
+namespace PerformanceCalculatorGUI;
+
+public interface IExtendedDifficultyCalculator
+{
+    Skill[] GetSkills();
+    DifficultyHitObject[] GetDifficultyHitObjects(IBeatmap beatmap, double clockRate);
+}