[Pharo-project] debugger <Restart> vs <Through> "Code simulation error"

I'm not sure if this is bug worthy or just a curiosity... In Workspace execute... self halt. x := 1. Then click <Debug>, <Through>, <Through>, <Restart>, <Through> to observe a "Code simulation error" cheers, Ben ( Pharo-1.4 #14333 / cogwin_r2522 / Window 7 )