bpo-42260: Improve error handling in _PyConfig_FromDict (GH-23488)

Author: serhiy-storchaka

Python/initconfig.c

@@ -1050,8 +1050,8 @@ _PyConfig_AsDict(const PyConfig *config)
 static PyObject*
 config_dict_get(PyObject *dict, const char *name)
 {
- PyObject *item = PyDict_GetItemString(dict, name);
- if (item == NULL) {
+ PyObject *item = _PyDict_GetItemStringWithError(dict, name);
+ if (item == NULL && !PyErr_Occurred()) {
  PyErr_Format(PyExc_ValueError, "missing config key: %s", name);
  return NULL;
  }
@@ -1085,7 +1085,7 @@ config_dict_get_int(PyObject *dict, const char *name, int *result)
  if (PyErr_ExceptionMatches(PyExc_TypeError)) {
  config_dict_invalid_type(name);
  }
- else {
+ else if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
  config_dict_invalid_value(name);
  }
  return -1;
@@ -1104,7 +1104,12 @@ config_dict_get_ulong(PyObject *dict, const char *name, unsigned long *result)
  }
  unsigned long value = PyLong_AsUnsignedLong(item);
  if (value == (unsigned long)-1 && PyErr_Occurred()) {
- config_dict_invalid_value(name);
+ if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+ config_dict_invalid_type(name);
+ }
+ else if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
+ config_dict_invalid_value(name);
+ }
  return -1;
  }
  *result = value;