Better error handling

[contempoinc]

A very, very small percentage of users are still experiencing timeouts https://cl.ly/0T3D182P1p2y which is a server issue, however this brought to my attention the wizard needs better error handling as it'll still hit the "Success" panel, even though the content step timed out, or say the plugins weren't actually downloaded due to permissions problems.

To the regular user which is our target they won't be viewing the Console panel in their browser developer tools, they'll just be left wondering what happened.

Something to think about for a future release.