fts5CorpusLookup top-level property
Hook installed by the engine: given a table and column name, return
the corpus-aware FTS5 index, or null when no active database is in
scope. Wired up by Database.executeStmt so that scalar functions
can reach back into the database without expression.dart importing
it (which would create a cycle).
Implementation
Fts5Index? Function(String table, String column)? fts5CorpusLookup;