ckanapi load datasets fails silently if owner_org is not found

If `owner_org` contains an ID which is not one of the available ones, ckanapi fails silently. Should there be a check?

Start with the ckanapi dataset-loading entry point and reproduce a load where owner_org contains an unavailable ID. Trace how that condition is handled and define completion as reporting the invalid organization instead of failing silently; add or update a regression test if the existing test layout provides one.

Written by the indexing model from the issue text.