Error is printed in console window if IDLE started from one.
>>> import idlelib.idle
# Select pathbrowser in File menu
Exception in Tkinter callback
Traceback (most recent call last):
  File "F:\dev\3x\lib\tkinter\__init__.py", line 1699, in __call__
    return self.func(*args)
  File "F:\dev\3x\lib\idlelib\editor.py", line 671, in open_path_browser
    pathbrowser.PathBrowser(self.flist)
  File "F:\dev\3x\lib\idlelib\pathbrowser.py", line 18, in __init__
    self.init(flist)
TypeError: init() takes 1 positional argument but 2 were given