Where did you get the "_" from?
This is the code from the tutorial:
func _process(delta):
var ball_pos = get_node("ball").get_pos()
var left_rect = Rect2( get_node("left").get_pos() - pad_size*0.5, pad_size )
var right_rect = Rect2( get_node("right").get_pos() - pad_size*0.5, pad_size )
This is your code
func process(delta):
_ var ball_pos = get_node("ball").get_pos()
var left_rect = Rect2( get_node("left").get_pos() - pad_size0.5, pad_size )
var right_rect = Rect2( get_node("right").get_pos() - pad_size0.5, pad_size )
Just compare and make sure they are exactly the same
