bpo-41384: Raise TclError in tkinter.OptionMenu (pythonGH-21601)

... when an unknown option is passed.  TypeError was being raised because a 2to3 fix was missing.

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

Lib/tkinter/__init__.py

@@ -3965,7 +3965,7 @@ def __init__(self, master, variable, value, *values, **kwargs):
         if 'command' in kwargs:
             del kwargs['command']
         if kwargs:
-            raise TclError('unknown option -'+kwargs.keys()[0])
+            raise TclError('unknown option -'+next(iter(kwargs)))
         menu.add_command(label=value,
                  command=_setit(variable, value, callback))
         for v in values:

Lib/tkinter/test/test_tkinter/test_widgets.py

@@ -307,6 +307,10 @@ class OptionMenuTest(MenubuttonTest, unittest.TestCase):
     def create(self, default='b', values=('a', 'b', 'c'), **kwargs):
         return tkinter.OptionMenu(self.root, None, default, *values, **kwargs)
 
+    def test_bad_kwarg(self):
+        with self.assertRaisesRegex(TclError, r"^unknown option -image$"):
+            tkinter.OptionMenu(self.root, None, 'b', image='')
+
 
 @add_standard_options(IntegerSizeTests, StandardOptionsTests)
 class EntryTest(AbstractWidgetTest, unittest.TestCase):

Misc/NEWS.d/next/Library/2020-07-26-21-18-43.bpo-41384.MlzIgV.rst

@@ -0,0 +1,2 @@
+Raise TclError instead of TypeError when an unknown option is passed to
+tkinter.OptionMenu.