debug build option WITH_PYTHON_UI_INFO, so you can right click and edit the python source for UI layout directly.

source/blender/python/generic/py_capi_utils.c

@@ -184,6 +184,15 @@ void PyC_FileAndNum(const char **filename, int *lineno)
 	}
 }
 
+void PyC_FileAndNum_Safe(const char **filename, int *lineno)
+{
+	if(!PYC_INTERPRETER_ACTIVE) {
+		return;
+	}
+
+	PyC_FileAndNum(filename, lineno);
+}
+
 /* Would be nice if python had this built in */
 PyObject *PyC_Object_GetAttrStringArgs(PyObject *o, Py_ssize_t n, ...)
 {