[Sketcher] Fix crash in SketcherObject::setDatum
[Sketcher] Fix crash in SketcherObject::setDatum

The variable newVals can't be used after std::move, fetch it from the
constraint it if an error occurs.
Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master