refactor: drop impossible-situation guard around tips.Release()

Both ISceneTipsProvider implementations resolve synchronously, so tips is
always assigned before any close path can run (review feedback). Also clears
the warning-ratchet findings in the touched files (nullable test fields,
redundant usings).

Author: alejandro-jimenez-dcl

Explorer/Assets/DCL/SceneLoadingScreens/ISceneTipsProvider.cs

@@ -1,6 +1,5 @@
 using Cysharp.Threading.Tasks;
 using System.Threading;
-using UnityEngine;
 
 namespace DCL.SceneLoadingScreens
 {

Explorer/Assets/DCL/SceneLoadingScreens/SceneLoadingScreenController.cs

@@ -137,14 +137,7 @@ protected override void OnViewClose()
             audioMixerVolumesController.UnmuteGroup(AudioMixerExposedParam.Chat_Volume);
 
             viewInstance!.ClearTips();
-
-            // Tips is null until the first load completes: a close racing that load must not
-            // release a default instance, and a later close must not release the same tips twice.
-            if (tips.Tips != null)
-            {
-                tips.Release();
-                tips = default;
-            }
+            tips.Release();
         }
 
         protected override async UniTask WaitForCloseIntentAsync(CancellationToken ct)

Explorer/Assets/DCL/SceneLoadingScreens/Tests/SceneLoadingScreenControllerInputBlockShould.cs

@@ -15,7 +15,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 using UnityEditor;
-using UnityEngine;
 using UnityEngine.Audio;
 using UnityEngine.TestTools;
 using Object = UnityEngine.Object;
@@ -53,11 +52,11 @@ public class SceneLoadingScreenControllerInputBlockShould
         // suppression is still active, instead of leaking into an unrelated later test.
         private const int FLUSH_FRAME_COUNT = 30;
 
-        private World world;
+        private World? world;
         private SingleInstanceEntity inputMapEntity;
-        private IInputBlock inputBlock;
-        private SceneLoadingScreenView viewInstance;
-        private AudioMixerVolumesController audioMixerVolumesController;
+        private IInputBlock? inputBlock;
+        private SceneLoadingScreenView? viewInstance;
+        private AudioMixerVolumesController? audioMixerVolumesController;
         private bool originalIgnoreFailingMessages;
 
         [OneTimeSetUp]
@@ -119,7 +118,7 @@ public void TearDown()
             if (viewInstance != null)
                 Object.DestroyImmediate(viewInstance.gameObject);
 
-            world.Dispose();
+            world!.Dispose();
 
             // Reset the static field so later tests in the same run aren't left with a stale in-memory
             // prefs instance (mirrors the reset half of the same established pattern).
@@ -203,10 +202,11 @@ public async Task ReleaseInputBlockWhenCloseRacesTheInitialTipsLoadAsync()
             }
             catch (NullReferenceException)
             {
-                // Pre-existing, separate defect (review.md finding 1): unpatched OnViewClose() calls
-                // tips.Release() on a still-default `tips` and throws. That defect is not what is under
-                // test here - what matters is whether the input block was released before that
-                // statement could run at all, which is asserted below regardless of this exception.
+                // An artifact of the never-resolving tips mock above: OnViewClose() calls tips.Release()
+                // on a still-default `tips` and throws. The real ISceneTipsProvider implementations
+                // resolve synchronously, so in production `tips` is always assigned before any close.
+                // It is not what is under test here - what matters is whether the input block was
+                // released before that statement could run at all, asserted below regardless.
             }
 
             Assert.That(ActiveKinds(), Is.EqualTo(ALL_KINDS),
@@ -221,7 +221,7 @@ public async Task ReleaseInputBlockWhenCloseRacesTheInitialTipsLoadAsync()
         }
 
         private SceneLoadingScreenController CreateController(ISceneTipsProvider tipsProvider) =>
-            new (() => viewInstance, tipsProvider, TimeSpan.Zero, audioMixerVolumesController, inputBlock);
+            new (() => viewInstance!, tipsProvider, TimeSpan.Zero, audioMixerVolumesController!, inputBlock!);
 
         private static SceneLoadingScreenController.Params CompletedParams()
         {
@@ -231,7 +231,7 @@ private static SceneLoadingScreenController.Params CompletedParams()
         }
 
         private InputMapComponent.Kind ActiveKinds() =>
-            inputMapEntity.GetInputMapComponent(world).Active;
+            inputMapEntity.GetInputMapComponent(world!).Active;
 
         private static InputMapComponent.Kind AllKinds()
         {