Blueprints from URL hangs daemon

[Sploder12]

Describe the bug
Using blueprints by specifying a URL will cause the daemon to hang.

To Reproduce

1. Run multipass launch https://github.com/canonical/multipass-blueprints/blob/main/v1/docker.yaml (or any valid blueprint URL)
2. See instance with generated name try to launch then timeout
3. Observe daemon hang

Expected behavior
The daemon replies with an error and does not try to start an undefined instance for bad blueprints. Or launches the blueprint correctly.

Logs
Logs are identical to that of a normal timeout error, except Cannot fetch image information: Unable to find an image matching hash "<hash>" appears occasionally.

Additional info

• OS: Linux

Additional context
Related to canonical/multipass-blueprints#66

Issue resides with error handling in mp::Daemon::create_vm
The hanging appears to be from using the url as the release which is probably a yaml file (although not necessarily).