I don't know who's reading this but have fun

extends Area2D

var mouse_radians
var sprite_sheet_hframes
# Called when the node enters the scene tree for the first time.
func _ready():
    sprite_sheet_hframes = $Sprite.hframes
    pass # Replace with function body.

# Called every frame. 'delta' is the elapsed time since the previous frame.
func _process(delta):
    get_mouse_radians()
    set_sprite()
    pass

func get_mouse_radians():
    mouse_radians = get_angle_to(get_global_mouse_position())
    if mouse_radians < 0:
        mouse_radians += PI + PI
    pass

func set_sprite():
    sprite_sheet_hframes = $Sprite.hframes
    var target_sprite = Maths.scale(mouse_radians, 0, 2*PI, 0, sprite_sheet_hframes)
    $Sprite.frame = int(target_sprite)