[APPWIZ] Aborting the download of Gecko will always display the error message box

With the recent cb499cd commit merged for the APPWIZ module, if the user decides to abort the download of the Gecko package on 2nd stage of the setup by clicking on "Cancel" button the message box will always be displayed, even though the machine has an internet conneciton.

I'll provide a patch once I found a way how to fix it.