PySimpleGUI crashes on simple statement

[interlocuteur]

Type of Issues :Bug

Operating System

Python version

PySimpleGUI Port and Version

Your Experience Levels In Months or Years

_______ Python programming experience
_________ Programming experience overall
_________ Have used another Python GUI Framework (tkiner, Qt, etc) previously (yes/no is fine)?

You have completed these steps:

• Read instructions on how to file an Issue
• Searched through main docs http://www.PySimpleGUI.org for your problem
• Searched through the readme for your specific port if not PySimpleGUI (Qt, WX, Remi)
• Looked for Demo Programs that are similar to your goal http://www.PySimpleGUI.com
• Note that there are also Demo Programs under each port on GitHub
• Run your program outside of your debugger (from a command line)
• Searched through Issues (open and closed) to see if already reported

Code or partial code causing the problem

Type of issue: bug
Operating system: Linux
Python version: 3.7.6
pySimpleGUI v4.15.2

The following program:
layout = [[sg.Multiline( default_text=None)]]
win = sg.Window( "", layout)
event,values = win.read()
will crash PySimpleGUI and the following tkinter will be generated:
_tkinter.TclError: wrong # args: should be ".!toplevel.!frame.!frame.!scrolledtext insert index chars ?tagList chars tagList ...?"
Yes! It's a user error. default_text should be a string, not None.
But PySimpleGUI should not crash on such a trivial error and the tkinter message is too cryptic to understand what is the cause.
PySimpleGUI should validate the default_text parameter during the Multiline object creation.

[PySimpleGUI]

Yea, that's a sucky thing to have happen any way you cut it. Terrible error message. Usually parameters like this are converted to strings but that still wouldn't produce the correct result in this case.