_tkinter.TclError: bitmap "tmp/asset/app.ico" not defined

[Duality4Y]

System:
$ lsb_release -a

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 22.04.3 LTS
Release: 22.04
Codename: jammy

python:

Python 3.10.12

after installing idle3 as mentioned in this issue: #2
running the following causes a stack trace and stop the program:
$ python main.py

Traceback (most recent call last):
  File "/home/robert/Documents/Code/WaveDromGen/main.py", line 4, in <module>
    wg = WaveDromUI()
  File "/home/robert/Documents/Code/WaveDromGen/WaveDromGen/WaveDromUI.py", line 56, in __init__
    root.iconbitmap(self.asset_dir + 'app.ico')
  File "/usr/lib/python3.10/tkinter/__init__.py", line 2109, in wm_iconbitmap
    return self.tk.call('wm', 'iconbitmap', self._w, bitmap)
_tkinter.TclError: bitmap "tmp/asset/app.ico" not defined