Failure to create endpoints doesn't emit warnings

[manthey]

When importing a docker image, it can import successfully but fail to create endpoints. This is confusing to the user, as the task is present in the UI but cannot be run.

This happens, for example, with a missing default entry for string inputs.

A simple fix would be to emit a warning message on endpoint creation after a job. It would be better to log this in the job output.