Removed verbose error logging for `yarn dev` failures
Removed verbose error logging for `yarn dev` failures

fixes https://github.com/TryGhost/Toolbox/issues/459

- in the situation where the `yarn dev` command fails, it pumps out a
  massive error message, which is incredibly distracting to the dev
  experience
- this changes the output to just be a log line with some suggestions on
  how to fix it

TryGhost/Ghost,TryGhost/Ghost,TryGhost/Ghost