Tighten up open/close in SQLite wrapper

[michaelsbradleyjr]

Per discussion in team chat, h/t @Bulat-Ziganshin:

sqlite3_close docs says that it will return non-OK value if some resources weren't closed. It's the great place to check correctness of the code dealing with DB, so don't ignore its return code

sqlite3_open_v2: Whether or not an error occurs when it is opened, resources associated with the database connection handle should be released by passing it to sqlite3_close() when it is no longer required