Why can't I use WindowManager's get_window?

[acdcbyl]

I am adding window open indicator to my bar and when I use the get_window method ignis stops completely and says window does not exist. But when I use ignis list-windows it shows that the window exists, I'm not sure if this is a bug or if I'm getting something wrong. Below is my code and the errors reported, I was hoping someone could help me out a bit, thanks a lot.

from ignis import widgets
from ignis.window_manager import WindowManager

window_manager = WindowManager.get_default()


class Applauncher(widgets.Button):
    def __init__(self, monitor: int, **kwargs):
        self._monitor = monitor
        self._window = window_manager.get_window("Applauncher")
        super().__init__(
            child=widgets.Box(
                child=[
                    widgets.Icon(pixel_size=15, icon_name="file-search-symbolic"),
                    widgets.Label(label="Applications", css_classes=["labelSmallBold"]),
                ]
            ),
            # on_click=self.__on_click,
            on_click=lambda x: window_manager.open_window("Applauncher"),
            css_classes=["bar_button"],
            **kwargs
        )

[acdcbyl]

God, I'm such an idiot. I'm so sorry that I handed in the wrong project.