Help With HTML5 Porting

When porting a friday night funkin mod to html5, the game opens but freezes after loading. I get this error in the console:
Kade Engine.js:127221 Uncaught TypeError: Cannot read properties of null (reading ‘set_x’)
at TitleState.update (Kade Engine.js:28382)
at TitleState.tryUpdate (Kade Engine.js:9047)
at flixel_FlxGame.update (Kade Engine.js:35074)
at flixel_FlxGame.step (Kade Engine.js:35049)
at flixel_FlxGame.onEnterFrame (Kade Engine.js:34983)
at openfl_display_Stage.__dispatchEvent (Kade Engine.js:4938)
at openfl_display_Stage.dispatch (Kade Engine.js:5751)
at openfl_display_Stage.broadcastEvent (Kade Engine.js:127040)
at openfl_display_Stage.onLimeRender (Kade Engine.js:128067)
at lime_app
$Void.dispatch (Kade Engine.js:104375)

Any ideas how i could fix this? Here is the source code for the mod:

Can you get mapping to work so you can find out the error line in the haxe code. I think you need to find which haxe class, line number is failing then someone will likely take a quick look… otherwise probably not.

work out all the related haxe line numbers and you will be lot closer to a fix

not sure if source mapping will help but anyway you can get the line numbers in haxe code will make it more likely someone will assist.