Youtube-dl code error pafy line 1892 in call

Question

CODE:

class CallWrapper:
    """Internal class. Stores function to call when some user
    defined Tcl function is called e.g. after an event occurred."""

    def __init__(self, func, subst, widget):
        """Store FUNC, SUBST and WIDGET as members."""
        self.func = func
        self.subst = subst
        self.widget = widget

    def __call__(self, *args):
        """Apply first function SUBST to arguments, than FUNC."""
        try:
            if self.subst:
                args = self.subst(*args)
            return self.func(*args) 
        except SystemExit:
            raise
        except:
            self.widget._report_exception()

Error:

File "/usr/lib/python3.8/tkinter/__init__.py", line 1892, in __call__
    return self.func(*args)