Problem

See #3895 (reply in thread) for background of this discussion.

Description

We'll make the following changes:

• Remove the warning logging when invalid sources are encountered.
• Add a warnings list to the search response when a partially invalid source list is passed.
• Raise a validation error when all sources passed are invalid, when not a single valid source is passed (e.g., all the sources are mispelled or disabled)

Alternatives

Additional context

Marking high priority for the logging improvements, because we don't need to fill our logging with these messages now that we have the answer we wanted.