Auto Load Error

DarwSK

Hi, so I am trying to make this little platformer game. I have been working on the Health Bar for a while now because I need to autoload my player script so I can use the "hp" variable in my Health Bar script but everytime I add the player script to Auto Load and start the game the game can not load and I get this error: Attempt to call function 'play' in base 'null instance' on a null instance.

Here is my player script:

extends KinematicBody2D

const SPEED = 350
const GRAVITY = 12
const JUMP_POWER  = -450
const FLOOR = Vector2(0, -1)
const MAXSPEED = 50
const OSTEP = preload("res://Scenes/Spear.tscn")

var velocity = Vector2()
var is_dead = false
var is_on_floor = is_on_floor()
var Enemy = preload("res://Scenes/Enemy.tscn")
var on_ground = false
var is_attacking = false
var hp = 3

func _physics_process(delta: float) -> void:
	if is_dead == false:	
	
		if Input.is_action_pressed("lavo"):    #pohyb dolava
			if is_attacking == false:
				velocity.x = -SPEED
				$AnimatedSprite.play("Run")
				$AnimatedSprite.flip_h = true
				if sign($Position2D.position.x) == 1:
					$Position2D.position.x *= -1
		elif Input.is_action_pressed("pravo"):   #pohyb doprava    
			if is_attacking == false:
				velocity.x = SPEED
				$AnimatedSprite.play("Run")
				$AnimatedSprite.flip_h = false
				if sign($Position2D.position.x) == -1:
					$Position2D.position.x *= -1
		else:    #nehybnost
			velocity.x = 0
			if on_ground == true && is_attacking == false:
				$AnimatedSprite.play("Idle")
			
		if Input.is_action_just_pressed("skok"):    #skok
			if is_attacking == false:
				if on_ground == true:
					$JumpSound.play()
					velocity.y = JUMP_POWER
					on_ground = false
				
		if Input.is_action_just_pressed("hod_ostep") && is_attacking == false:    #hodenie ostepu
			is_attacking = true
			$SpearThrow.play()
			$AnimatedSprite.play("Attack")
			var ostep = OSTEP.instance()
			if sign($Position2D.position.x) == 1:
				ostep.set_ostep_direction(1)
			else:
				ostep.set_ostep_direction(-1)
			get_parent().add_child(ostep)
			ostep.position = $Position2D.global_position
					
					
		for i in range (get_slide_count()):
			var collision = get_slide_collision(i)
			if collision.collider.is_in_group("Enemy"):
				var enemy = collision.collider
				if Vector2.UP.dot(collision.normal) > 0.1:
					enemy.squash()
					velocity.y = JUMP_POWER
		
		velocity.y += GRAVITY
		
		if is_on_floor():    #skok
			on_ground = true
		else:
			if is_attacking == false:
				on_ground = false
				$AnimatedSprite.play("Jump")
				if velocity.y <= 0:
					$AnimatedSprite.play("Jump")
	
	
	velocity = move_and_slide(velocity, FLOOR, true)
	
	
func _on_EnemyDetector_body_entered(body):    #zabitie hraca nepriatelom
	if "Enemy" in body.name and is_dead == false:
		$Hurt.play()
		hp -= 1
		
		if hp == 0:
			_dead()
	elif "Enemy" in body.name and is_dead == true:
		$Timer.start()
		

	
func _dead():
			is_dead == true    #proces smrti
			set_physics_process(false)
			$AnimatedSprite.play("MOREDEAD")
			get_node("CollisionShape2D").disabled = true
			$EnemyDetector/CollisionShape2D.call_deferred("set_disabled", true)
			$DeathSound.play()
			$Timer.start()
			

func _on_Timer_timeout() -> void:    #prepnutie do menu po smrti
	get_tree().change_scene("res://Scenes/TitleScreen.tscn")

func _on_AnimatedSprite_animation_finished() -> void:

Can someone help please, I have been stuck on this for a while now.
Thanks.

Megalomaniak

You probably shouldn't have it as autoload.

Whatever is an autoload is going to be loaded well before the other things, and will not find the other nodes and thus complain about null instances. You could implement checks such as is valid instance or is in tree or such(and that's a good idea/practice anyways) but honestly there's only so much that should be an autoload/global in the first place. If it can be avoided, I'd avoid making things unnecessarily autoloads.

Your instinct might be to think that having something be an autoload is going to make your life easier, but in most cases it likely just makes your life more difficult.

As a compromise you can have a globals script set as a autoload that can hold a variable and a function that will get and store the nodepath to your player node/script in that variable so you can more conveniently access your player node when and where needed. That's at least marginally better.

What you then have is your player script on ready connect a signal and call that signal on the global to let it know that it's been instanced and then in that method triggered by the signal it gets the players nodepath and stores it in the variable.