since its a steel stove I would get it welded...no reason you cant still use until then though, just will be sucking a little extra air... I would drill a small hole at the end of the crack to keep it from continuing until you can get it welded.
looks like it started at the corner of the "cut out" for the door, and it looks like it also cracked the sealing flange for the door...that looks like too much of a difference for the gasket to seal...