I get Invalid Error: "LONGVARCHAR" when selecting from "LONGVARCHAR" columns in an attached SQLite database. To reproduce:

Create a SQLite database:

echo "CREATE TABLE tbl (long_strings LONGVARCHAR); INSERT INTO tbl VALUES ('abc'), ('def');" | sqlite3 test.db

Attach it from DuckDB (./build/release/duckdb -unsigned):

D LOAD 'build/release/extension/sqlite_scanner/sqlite_scanner.duckdb_extension';
D CALL sqlite_attach('test.db');
D SELECT * FROM tbl;
Error: Invalid Error: "LONGVARCHAR"