Flood Fill Method bug

[mystic pelican]

• Red Pixel: Dungeon generator, irrelevant for this bug.
• Green Pixel: "Found" tile. Tiles should only be found if they're adjacent.
• Yellow Pixel: "Unfound" tile. should be found if adjacent to a green tile.

Here is the full relevant code:

extends Area2D

var openList = [];
var closedList = [];

func initSelf():
    z_index =2000;
    var startList = get_overlapping_areas();
    openList.append_array(startList);

func stepForward():
    var currentTile = openList[0];
    global_position = currentTile.global_position
    currentTile.get_child(0).color = Color(0,1,0);
    closedList.append(currentTile);
    openList.remove_at(0);
    
    var surroundingTiles = get_overlapping_areas();
    print("Surrounding Tiles: "+str(surroundingTiles));
    for value in surroundingTiles:
        if !closedList.has(value):
            if !openList.has(value):
                openList.append(value);
    print("Open list: "+str(openList));

var state = "init";
func _physics_process(_delta):
    await get_tree().physics_frame
    
    if state=="init":
        initSelf();
        state = "null";
    
    if openList.size() > 0:
        stepForward();
        print(closedList.size()) //DEBUG
    else:
        print(get_parent().get_child(0).get_children().size()); //DEBUG
        print(closedList.size() == get_parent().get_child(0).get_children().size()); //DEBUG
        queue_free();