Compilation warning in cf3/ui/graphics/PythonPreCompiler.cpp

[wdeconinck]

The warning goes as follows:

/Users/willem/workspace/coolfluid3/stable/kernel/cf3/ui/graphics/PythonPreCompiler.cpp:54:1: warning: control may reach end of non-void function [-Wreturn-type]

The function this is about is listed :

const QString PythonPreCompiler::try_compile(const QString & line) const {
  boost::python::handle<> src=boost::python::handle<>(boost::python::allow_null(Py_CompileString(line.toStdString().c_str(), "test", Py_single_input)));
  if (NULL != src.get())
    return "";
  PyObject *exc,*val,*trb,*obj;
  char* error;
  PyErr_Fetch(&exc, &val, &trb);
  if (NULL != val){
    if (PyArg_ParseTuple (val, "sO", &error, &obj)){
      return error;
    }else{
      const char* val_str=PyString_AsString(PyObject_Str(val));
      return val_str;
    }
  }
  PyErr_Clear();
}

I would fix it myself, but don't know what the return of this function should be.
Please fix this Vivian :)