"Invalid network options supplied" error devoid of context

When launching an instance with incorrect `--network` options (e.g. wrong network name), the error is a dry:

```plain
launch failed: Invalid arguments supplied
Invalid network options supplied
```

We could do much better here :)

Reproduce the failure by launching an instance with an incorrect --network option, such as a wrong network name, and trace the validation and error-reporting path. Done means the command reports which network option or value is invalid and provides useful context instead of only saying "Invalid network options supplied."

Written by the indexing model from the issue text.