attempt to enforce str/list[str] condition on modules list

this actually did not matter for the code, I guess. The only reason to change it was because mypy was complaining because mypy doesn't allow redefinition that way (at least with these settings). But instead of beating mypy into doing what I want, I just made the types follow the error message here.

Author: wyattscarpenter

mypy/config_parser.py

@@ -494,17 +494,20 @@ def destructure_overrides(toml_data: _TomlDictDict) -> _ParserHelper:
                 "section, but no module to override was specified."
             )
 
-        if isinstance(override["module"], str):
-            modules = [override["module"]]
-        elif isinstance(override["module"], list):
-            modules = override["module"]
-        else:
+        def complain_str_list() -> Never:
             raise MypyConfigTOMLValueError(
                 "toml config file contains a [[tool.mypy.overrides]] "
                 "section with a module value that is not a string or a list of "
                 "strings"
             )
 
+        if isinstance(override["module"], str):
+            modules = [override["module"]]
+        elif isinstance(override["module"], list):
+            modules = [m if isinstance(m, str) else complain_str_list() for m in override["module"]]
+        else:
+            complain_str_list()
+
         for module in modules:
             module_overrides = override.copy()
             del module_overrides["module"]