bpo-34649: Add missing NULL checks to _encoded_const() (GH-9225)

Reported by Svace static analyzer. (cherry picked from commit 6f82bff) Co-authored-by: Alexey Izbyshev <izbyshev@ispras.ru>

Author: 2 people

Modules/_json.c

@@ -1893,23 +1893,23 @@ _encoded_const(PyObject *obj)
  if (s_null == NULL) {
  s_null = PyString_InternFromString("null");
  }
- Py_INCREF(s_null);
+ Py_XINCREF(s_null);
  return s_null;
  }
  else if (obj == Py_True) {
  static PyObject *s_true = NULL;
  if (s_true == NULL) {
  s_true = PyString_InternFromString("true");
  }
- Py_INCREF(s_true);
+ Py_XINCREF(s_true);
  return s_true;
  }
  else if (obj == Py_False) {
  static PyObject *s_false = NULL;
  if (s_false == NULL) {
  s_false = PyString_InternFromString("false");
  }
- Py_INCREF(s_false);
+ Py_XINCREF(s_false);
  return s_false;
  }
  else {