RQ worker fails silently on frontend when config file not present

the UI will appear to "work," but no jobs can be executed because of an error like this:
```
FileNotFoundError: [Errno 2] Unable to load configuration file (No such file or directory): '/config.py'
```

The frontend should be able to gracefully notify the user of an issue, so that they are not left wondering why their VM was not created when they get a popup (incorrectly) confirming creation.