Upgrading to CustomTkinter 5.0.1 breaks my app (KeyError: 'CTk')

Hi. I just upgraded to CustomTkinter 5.0.1, and now when I launch my app, I get a dictionary lookup error:

The stack trace tells me that it's the last line of these:

...
import tkinter as tk
from tkinter import filedialog as fd
import customtkinter as ctk
...

class DCCMView(ctk.CTk):
    """Class to act as our visual interface."""

    def __init__(self, mvc_controller, *args, **kwargs):
        super().__init__(*args, **kwargs)                                         <<< Line 1705

This is the error stack:

  File "D:\Development\PycharmProjects\dccm\dccm.py", line 2535, in <module>
    controller = DCCMControl(app_home, mode=run_mode, db_file_path=db_file, connection_identifier=connection_identifier)
  File "D:\Development\PycharmProjects\dccm\dccm.py", line 1246, in __init__
    self.mvc_view = DCCMView(mvc_controller=self)
  File "D:\Development\PycharmProjects\dccm\dccm.py", line 1705, in __init__
    super().__init__(*args, **kwargs)
  File "D:\Development\PycharmProjects\dccm\venv\lib\site-packages\customtkinter\windows\ctk_tk.py", line 51, in __init__
    self._fg_color = ThemeManager.theme["CTk"]["fg_color"] if fg_color is None else self._check_color_type(fg_color)
KeyError: 'CTk'

This also occurs on 5.0.0. Reverting back to 4.6.3 causes the app to work OK.

Regards,

Clive

Start at customtkinter/windows/ctk_tk.py line 51, where DCCMView's ctk.CTk initialization raises the KeyError. Reproduce the failure with the shown DCCMView example under CustomTkinter 5.0.0 or 5.0.1, then compare behavior with 4.6.3. Done means the application starts without the 'CTk' lookup error after upgrading.