gh-145821: properly raise OptionError in Option._check_callback when callback_kwargs is invalid

Lib/optparse.py

@@ -706,7 +706,7 @@ def _check_callback(self):
                 not isinstance(self.callback_kwargs, dict)):
                 raise OptionError(
                     "callback_kwargs, if supplied, must be a dict: not %r"
-                    % self.callback_kwargs, self)
+                    % (self.callback_kwargs,), self)
         else:
             if self.callback is not None:
                 raise OptionError(

Lib/test/test_optparse.py

@@ -301,6 +301,14 @@ def test_callback_kwargs_no_dict(self):
                      'callback': self.dummy,
                      'callback_kwargs': 'foo'})
 
+    def test_callback_kwargs_tuple_not_dict(self):
+        self.assertOptionError(
+            "option -b: callback_kwargs, if supplied, "
+            "must be a dict: not (1, 2)",
+            ["-b"], {'action': 'callback',
+                     'callback': self.dummy,
+                     'callback_kwargs': (1, 2)})
+
     def test_no_callback_for_action(self):
         self.assertOptionError(
             "option -b: callback supplied ('foo') for non-callback option",

Misc/NEWS.d/next/Library/2026-03-11-14-14-27.gh-issue-145821.xWSIjR.rst

@@ -0,0 +1,2 @@
+:mod:`optparse`: raise :exc:`~optparse.OptionError` instead of :exc:`TypeError`
+when ``callback_kwargs`` is not a dictionary.