[hand] Add bash error checking function and check for errors after all commands for archive creation
[hand] Add bash error checking function and check for errors after all commands for archive extraction
[hand] Pointless final_command free in archive creation
[hand] Make sure that the handler config dialog loads with the first handler selected in the treeview

Fixing a bug where the old code would load the first handler, but not via treeview selection - so you
make a change and apply, but as there is no selection the first handler is loaded, nuking your change