enable_fts() exhausts iterator columns before populating the index #902

Problem

Table.enable_fts() accepts columns: Iterable[str], but passing a one-shot iterator raises sqlite3.OperationalError: near ")": syntax error. The same columns supplied as a list work. The FTS virtual table has already been created when the error occurs, so a retry without replace=True also encounters an existing table.

Reproduced locally against main 9c66bafa52ae23d40499c74b0db3b635bcddb876, Python 3.12.14, using an in-memory database:

from sqlite_utils import Database

db = Database(memory=True)
table = db["notes"].insert({"text": "hello"})
table.enable_fts(iter(["text"]))
# sqlite3.OperationalError: near ")": syntax error

Replacing iter(["text"]) with ["text"] succeeds and list(table.search("hello")) returns the record. I reproduced the failure with both FTS4 and FTS5, with and without create_triggers=True.

The iterable is consumed while building CREATE VIRTUAL TABLE, then passed to populate_fts(). Trigger construction also reuses it. Materializing the columns once would preserve the declared iterable contract.

AI assistance: OpenAI Codex inspected the code and ran this reproduction. No live service, user database, or external model call was used.