I am trying to launch dialogs for selecting files, resp. directories from jupyter notebook cells.

while I managed to successfully load files that were selected via a Qt5 dialog, trying to select a directory in analogous manner keeps killing the kernel

Here are the cells for the file selection:

%%writefile  'openCSV.py'

from sys import executable, argv
from subprocess import check_output
from PyQt5.QtWidgets import QFileDialog, QApplication

# sys.executable is just the path to the running python executable

def openCSV(directory='./'):
    """Open a file dialog, starting in the given directory, and return
    the chosen filename"""
    # run this exact file in a separate process, and grab the result
    file = check_output([executable, __file__, directory])
    return file.strip()

if __name__ == "__main__":
    directory = argv[1]
    app = QApplication([directory])
    fname = QFileDialog.getOpenFileName(None, "Select a file...", 
            directory, filter="CSV files (*.csv)")
    print(fname[0])

import openCSV
f = openCSV.openCSV('C:/Users/Me/Documents/')
print(f'{f=}')

And here the failing attempt to select a directory:

%%writefile selectFolder
from sys import executable, argv
from subprocess import check_output
from PyQt5.QtWidgets import QFileDialog, QApplication

def selectFolder(directory='./'):
    folder = check_output([executable, __file__, directory])
    return folder.strip()

if __name__ == "__main__":
    directory = argv[1]
    app = QApplication([directory])
    folderpath = QFileDialog.getExistingDirectory(None, "Select folder")

import selectFolder
d = selectFolder.selectFolder()
print(f'{d=}')

As I’m new to the topic my guess is that its a minor thing that needs to be changed, but what is it, resp. what is the essential difference between selecting files and folders?