Update Lib/configparser.py

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Author: lpyu001

Lib/configparser.py

@@ -1224,7 +1224,7 @@ def _convert_to_boolean(self, value):
         """
         if value is None:
             raise ValueError('Not a boolean: None')
-        if value.lower() not in self.BOOLEAN_STATES:
+        if value is None or value.lower() not in self.BOOLEAN_STATES:
             raise ValueError('Not a boolean: %s' % value)
         return self.BOOLEAN_STATES[value.lower()]