Fix memory leak in _handle_string_or_none_result

The function did not decref the Python object on type error paths,
resulting in a reference count leak. This caused memory to accumulate
over time. Added Py_XDECREF on all early return paths to properly free
the Python object reference and prevent leaks.

src/plugins/python_plugins.c

@@ -900,6 +900,8 @@ _python_type_error(ProfPlugin* plugin, char* hook, char* type)
     g_string_free(err_msg, TRUE);
 }
 
+// Converts a Python string or None result to a C string and decreases the Python object's reference count.
+// If the result is NULL, or not a string/unicode/bytes/None, logs an error and returns NULL.
 static char*
 _handle_string_or_none_result(ProfPlugin* plugin, PyObject* result, char* hook)
 {
@@ -910,18 +912,16 @@ _handle_string_or_none_result(ProfPlugin* plugin, PyObject* result, char* hook)
     }
 #ifdef PY_IS_PYTHON3
     if (result != Py_None && !PyUnicode_Check(result) && !PyBytes_Check(result)) {
-        allow_python_threads();
-        _python_type_error(plugin, hook, "string, unicode or None");
-        return NULL;
-    }
 #else
     if (result != Py_None && !PyUnicode_Check(result) && !PyString_Check(result)) {
+#endif
+        Py_XDECREF(result);
         allow_python_threads();
         _python_type_error(plugin, hook, "string, unicode or None");
         return NULL;
     }
-#endif
     char* result_str = python_str_or_unicode_to_string(result);
+    Py_XDECREF(result);
     allow_python_threads();
     return result_str;
 }