The audiobook NULL-poster work wrapped nullable string columns in bare
COALESCE(...) expressions inside itemColumns/qualifiedItemColumns. Postgres
names an unaliased COALESCE output "coalesce", so the search query's scored
CTE stopped exposing poster_path etc. and every /catalog?source=query
request failed with SQLSTATE 42703, surfacing as a 500.
Alias each coalesced column back to its own name, deduplicate the three
copies of the column list into a shared itemColumnNames slice, and give the
search CTE's GROUP BY its own alias-free reference list (output aliases are
invalid in GROUP BY). Regression tests pin both invariants.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
