chore: Add null safety to PlayState and LoadingState

source/funkin/play/GameOverSubState.hx

@@ -162,7 +162,7 @@ class GameOverSubState extends MusicBeatSubState
     if ((parentPlayState?.isMinimalMode ?? true)) {}
     else
     {
-      boyfriend = parentPlayState?.currentStage.getBoyfriend(true);
+      boyfriend = parentPlayState?.currentStage?.getBoyfriend(true);
       if (boyfriend != null)
       {
         boyfriend.canPlayOtherAnims = true;
@@ -193,10 +193,9 @@ class GameOverSubState extends MusicBeatSubState
     });
   }
 
-  @:nullSafety(Off)
   function setCameraTarget():Void
   {
-    if ((parentPlayState?.isMinimalMode ?? true) || boyfriend == null) return;
+    if (parentPlayState == null || parentPlayState.isMinimalMode || boyfriend == null) return;
 
     // Assign a camera follow point to the boyfriend's position.
     cameraFollowPoint = new FlxObject(parentPlayState.cameraFollowPoint.x, parentPlayState.cameraFollowPoint.y, 1, 1);
@@ -207,6 +206,7 @@ class GameOverSubState extends MusicBeatSubState
     cameraFollowPoint.y += offsets[1];
     add(cameraFollowPoint);
 
+    @:nullSafety(Off)
     FlxG.camera.target = null;
     FlxG.camera.follow(cameraFollowPoint, LOCKON, Constants.DEFAULT_CAMERA_FOLLOW_RATE / 2);
     targetCameraZoom = (parentPlayState?.currentStage?.camZoom ?? 1.0) * boyfriend.getDeathCameraZoom();
@@ -394,7 +394,7 @@ class GameOverSubState extends MusicBeatSubState
             // Readd Boyfriend to the stage.
             boyfriend.isDead = false;
             remove(boyfriend);
-            parentPlayState?.currentStage.addCharacter(boyfriend, BF);
+            parentPlayState?.currentStage?.addCharacter(boyfriend, BF);
           }
 
           // Snap reset the camera which may have changed because of the player character data.
@@ -564,11 +564,11 @@ class GameOverSubState extends MusicBeatSubState
         PlayStatePlaylist.reset();
       }
 
-      var stickerPackId:Null<String> = parentPlayState?.currentChart.stickerPack;
+      var stickerPackId:Null<String> = parentPlayState?.currentChart?.stickerPack;
 
       if (stickerPackId == null)
       {
-        var playerCharacterId:Null<String> = PlayerRegistry.instance.getCharacterOwnerId(parentPlayState?.currentChart.characters.player);
+        var playerCharacterId:Null<String> = PlayerRegistry.instance.getCharacterOwnerId(parentPlayState?.currentChart?.characters.player);
         var playerCharacter:Null<PlayableCharacter> = PlayerRegistry.instance.fetchEntry(playerCharacterId ?? Constants.DEFAULT_CHARACTER);
 
         if (playerCharacter != null)

source/funkin/play/GitarooPause.hx

@@ -18,9 +18,9 @@ class GitarooPause extends MusicBeatState
 
   var replaySelect:Bool = false;
 
-  var previousParams:PlayStateParams;
+  var previousParams:Null<PlayStateParams>;
 
-  public function new(previousParams:PlayStateParams):Void
+  public function new(?previousParams:PlayStateParams):Void
   {
     super();
 

source/funkin/play/components/HealthIcon.hx

@@ -151,10 +151,12 @@ class HealthIcon extends FunkinSprite
    */
   public function toggleOldIcon():Void
   {
+    final playState:Null<PlayState> = PlayState.instance;
+    if (playState == null || playState.currentStage == null) return;
     if (characterId == 'bf-old')
     {
-      isPixel = PlayState.instance.currentStage.getBoyfriend().isPixel;
-      PlayState.instance.currentStage.getBoyfriend().initHealthIcon(false);
+      isPixel = playState.currentStage.getBoyfriend()?.isPixel ?? false;
+      playState.currentStage.getBoyfriend()?.initHealthIcon(false);
     }
     else
     {

source/funkin/play/notes/Strumline.hx

@@ -97,9 +97,9 @@ class Strumline extends FlxSpriteGroup
   /**
    * Reset the scroll speed to the current chart's scroll speed.
    */
-  public function resetScrollSpeed():Void
+  public function resetScrollSpeed(?newScrollSpeed:Float):Void
   {
-    scrollSpeed = PlayState.instance?.currentChart?.scrollSpeed ?? 1.0;
+    scrollSpeed = newScrollSpeed ?? PlayState.instance?.currentChart?.scrollSpeed ?? 1.0;
   }
 
   var _conductorInUse:Null<Conductor>;
@@ -184,7 +184,7 @@ class Strumline extends FlxSpriteGroup
 
   static final BACKGROUND_PAD:Int = 16;
 
-  public function new(noteStyle:NoteStyle, isPlayer:Bool)
+  public function new(noteStyle:NoteStyle, isPlayer:Bool, ?scrollSpeed:Float)
   {
     super();
 
@@ -243,7 +243,7 @@ class Strumline extends FlxSpriteGroup
     this.refresh();
 
     this.onNoteIncoming = new FlxTypedSignal<NoteSprite->Void>();
-    resetScrollSpeed();
+    resetScrollSpeed(scrollSpeed);
 
     for (i in 0...KEY_COUNT)
     {

source/funkin/ui/transition/LoadingState.hx

@@ -12,6 +12,7 @@ import funkin.graphics.shaders.ScreenWipeShader;
 import funkin.play.PlayState;
 import funkin.play.PlayStatePlaylist;
 import funkin.play.song.Song.SongDifficulty;
+import funkin.play.stage.Stage;
 import haxe.io.Path;
 import lime.app.Future;
 import lime.app.Promise;
@@ -21,6 +22,7 @@ import lime.utils.Assets as LimeAssets;
 import openfl.filters.ShaderFilter;
 import openfl.utils.Assets as OpenFLAssets;
 
+@:nullSafety
 class LoadingState extends MusicBeatSubState
 {
   inline static var MIN_TIME = 1.0;
@@ -30,18 +32,21 @@ class LoadingState extends MusicBeatSubState
   var target:NextState;
   var playParams:Null<PlayStateParams>;
   var stopMusic:Bool = false;
-  var callbacks:MultiCallback;
+  var callbacks:Null<MultiCallback>;
   var danceLeft:Bool = false;
 
   var loadBar:FlxSprite;
   var funkay:FlxSprite;
 
-  function new(target:NextState, stopMusic:Bool, playParams:Null<PlayStateParams> = null)
+  function new(target:NextState, stopMusic:Bool, ?playParams:PlayStateParams)
   {
     super();
     this.target = target;
     this.playParams = playParams;
     this.stopMusic = stopMusic;
+
+    this.loadBar = new FunkinSprite(0, FlxG.height - 20).makeSolidColor(0, 10, 0xFFff16d2);
+    this.funkay = FunkinSprite.create('funkay');
   }
 
   override function create():Void
@@ -49,14 +54,12 @@ class LoadingState extends MusicBeatSubState
     var bg:FunkinSprite = new FunkinSprite().makeSolidColor(FlxG.width, FlxG.height, 0xFFcaff4d);
     add(bg);
 
-    funkay = FunkinSprite.create('funkay');
     funkay.setGraphicSize(0, FlxG.height);
     funkay.updateHitbox();
     add(funkay);
     funkay.scrollFactor.set();
     funkay.screenCenter();
 
-    loadBar = new FunkinSprite(0, FlxG.height - 20).makeSolidColor(0, 10, 0xFFff16d2);
     add(loadBar);
 
     initSongsManifest().onComplete(function(lib) {
@@ -66,15 +69,21 @@ class LoadingState extends MusicBeatSubState
       if (playParams != null)
       {
         // Load and cache the song's charts.
-        if (playParams.targetSong != null)
+        if (playParams.targetSong == null)
         {
-          playParams.targetSong.cacheCharts(true);
+          throw 'Invalid parameter: Target song should not be null';
         }
 
+        playParams.targetSong.cacheCharts(true);
+
         // Preload the song for the play state.
         var difficulty:String = playParams.targetDifficulty ?? Constants.DEFAULT_DIFFICULTY;
         var variation:String = playParams.targetVariation ?? Constants.DEFAULT_VARIATION;
-        var targetChart:SongDifficulty = playParams.targetSong?.getDifficulty(difficulty, variation);
+        var targetChart:Null<SongDifficulty> = playParams.targetSong.getDifficulty(difficulty, variation);
+        if (targetChart == null)
+        {
+          throw 'Couldn\'t retrieve chart data for song "${playParams.targetSong.songName}" on difficulty "$difficulty" and variation "$variation"';
+        }
         var instPath:String = targetChart.getInstPath(playParams.targetInstrumental);
         var voicesPaths:Array<String> = targetChart.buildVoiceList();
 
@@ -105,9 +114,9 @@ class LoadingState extends MusicBeatSubState
       // library.types.set(symbolPath, SOUND);
       // @:privateAccess
       // library.pathGroups.set(symbolPath, [library.__cacheBreak(symbolPath)]);
-      var callback = callbacks.add('song:' + path);
+      var callback = callbacks?.add('song:' + path);
       Assets.loadSound(path).onComplete(function(_) {
-        callback();
+        if (callback != null) callback();
       });
     }
   }
@@ -120,9 +129,9 @@ class LoadingState extends MusicBeatSubState
       @:privateAccess
       if (!LimeAssets.libraryPaths.exists(library)) throw 'Missing library: ' + library;
 
-      var callback = callbacks.add('library:' + library);
+      var callback = callbacks?.add('library:' + library);
       Assets.loadLibrary(library).onComplete(function(_) {
-        callback();
+        if (callback != null) callback();
       });
     }
   }
@@ -177,6 +186,7 @@ class LoadingState extends MusicBeatSubState
   function onLoad():Void
   {
     // Stop the instrumental.
+    @:nullSafety(Off)
     if (stopMusic && FlxG.sound.music != null)
     {
       FlxG.sound.music.destroy();
@@ -197,7 +207,7 @@ class LoadingState extends MusicBeatSubState
 
   static function getSongPath():String
   {
-    return Paths.inst(PlayState.instance.currentSong.id);
+    return Paths.inst(PlayState.instance?.currentSong.id ?? throw 'Cannot retrieve song path');
   }
 
   static var stageDirectory:String = "shared";
@@ -211,10 +221,10 @@ class LoadingState extends MusicBeatSubState
    */
   public static function loadPlayState(params:PlayStateParams, shouldStopMusic = false, asSubState = false, ?onConstruct:PlayState->Void):Void
   {
-    var daChart:Null<SongDifficulty> = params.targetSong.getDifficulty(params.targetDifficulty ?? Constants.DEFAULT_DIFFICULTY,
+    var daChart:Null<SongDifficulty> = params.targetSong?.getDifficulty(params.targetDifficulty ?? Constants.DEFAULT_DIFFICULTY,
       params.targetVariation ?? Constants.DEFAULT_VARIATION);
 
-    var daStage = funkin.data.stage.StageRegistry.instance.fetchEntry(daChart?.stage ?? Constants.DEFAULT_STAGE);
+    var daStage:Null<Stage> = funkin.data.stage.StageRegistry.instance.fetchEntry(daChart?.stage ?? Constants.DEFAULT_STAGE);
     stageDirectory = daStage?._data?.directory ?? "shared";
     Paths.setCurrentLevel(stageDirectory);
 
@@ -249,6 +259,7 @@ class LoadingState extends MusicBeatSubState
     }
     #else
     // All assets preloaded, switch directly to play state (defualt on other targets).
+    @:nullSafety(Off)
     if (shouldStopMusic && FlxG.sound.music != null)
     {
       FlxG.sound.music.destroy();
@@ -257,7 +268,7 @@ class LoadingState extends MusicBeatSubState
 
     // Load and cache the song's charts.
     // Don't do this if we already provided the music and charts.
-    if (params?.targetSong != null && !params.overrideMusic)
+    if (!(params.overrideMusic ?? false))
     {
       params.targetSong.cacheCharts(true);
     }
@@ -272,7 +283,8 @@ class LoadingState extends MusicBeatSubState
       var songDifficulty = params.targetSong.getDifficulty(params.targetDifficulty, params.targetVariation);
       if (songDifficulty != null)
       {
-        var noteStyle = NoteStyleRegistry.instance.fetchEntry(songDifficulty.noteStyle);
+        var noteStyle = NoteStyleRegistry.instance.fetchEntry(songDifficulty.noteStyle ?? '');
+        if (noteStyle == null) noteStyle = NoteStyleRegistry.instance.fetchDefault();
         FunkinMemory.cacheNoteStyle(noteStyle);
       }
 
@@ -439,7 +451,7 @@ class LoadingState extends MusicBeatSubState
     var libraryPaths = LimeAssets.libraryPaths;
     if (libraryPaths.exists(id))
     {
-      path = libraryPaths[id];
+      path = libraryPaths[id] ?? path;
       rootPath = Path.directory(path);
     }
     else
@@ -490,17 +502,18 @@ class LoadingState extends MusicBeatSubState
   }
 }
 
+@:nullSafety
 class MultiCallback
 {
   public var callback:Void->Void;
-  public var logId:String = null;
+  public var logId:Null<String>;
   public var length(default, null) = 0;
   public var numRemaining(default, null) = 0;
 
   var unfired = new Map<String, Void->Void>();
   var fired = new Array<String>();
 
-  public function new(callback:Void->Void, logId:String = null)
+  public function new(callback:Void->Void, ?logId:String)
   {
     this.callback = callback;
     this.logId = logId;
@@ -511,8 +524,7 @@ class MultiCallback
     id = '$length:$id';
     length++;
     numRemaining++;
-    var func:Void->Void = null;
-    func = function() {
+    var func:Void->Void = function() {
       if (unfired.exists(id))
       {
         unfired.remove(id);