[3.10] bpo-34266: [pdb] handle ValueError from shlex.split() (GH-26656) (GH-27006)

(cherry picked from commit d968a638fc)

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>

Lib/test/test_pdb.py

@@ -1800,6 +1800,21 @@ def bœr():
             '(Pdb) ',
         ])
 
+    def test_issue34266(self):
+        '''do_run handles exceptions from parsing its arg'''
+        def check(bad_arg, msg):
+            commands = "\n".join([
+                f'run {bad_arg}',
+                'q',
+            ])
+            stdout, _ = self.run_pdb_script('pass', commands + '\n')
+            self.assertEqual(stdout.splitlines()[1:], [
+                '-> pass',
+                f'(Pdb) *** Cannot run {bad_arg}: {msg}',
+                '(Pdb) ',
+            ])
+        check('\\', 'No escaped character')
+        check('"', 'No closing quotation')
 
     def test_issue42384(self):
         '''When running `python foo.py` sys.path[0] is an absolute path. `python -m pdb foo.py` should behave the same'''