New environment descovery does not respect the raise on error property

If the discovery process using image labels is run on a machine without docker running or if the daemon is not running, it will fail as expected however the error handling does not follow the raise on error property.

To reproduce, call beat editor refresh-env on a machine without docker or with the daemon stopped.

A current workaround is to create the .environments.json file in the prefix with {} as its content.