to get signal / event whenever repository is not available / no internet connection

So whenever the repository is not available OR user has no connection, there will be a warning shown "Cannot retrieve remote tree"

But installer doesn't get any signal for this event. 

So I'm asking if we can add signal whenever repository cant retrieved.

I have tried metaJobInfoMessage, metaJobProgress and metaJobTotalProgress, but it doesn't tell me whenever repository is can't be retrieved.