I know this isn't explicitly part of your PR, but I just read the following:
Quote: "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." 
Source: http://www.sqlite.org/c3ref/open.html

Accordingly, could you please add a "sqlite3_close(db_)" before this error is thrown? We need not check for SQLITE_OK here because it's already in error.