Check if the showcase is still available before validating

[kovalch]

Would it possible to add an additional check for the existing of the showcase here, something like:
`

check if showcase_id is in context or is valid

if 'package' not in context or not context['package']:
    log.warning("Showcase is not available. Showcase ID: {0}".format(
        data_dict.get('showcase_id')))
    return []

`

We have the situations that the showcase was deleted and was not reindexed, so we still get the deleted-showcase id here and try to validate it