Close connection immediately after failed open

[katafrakt]

Per documentation sqlite3_close_v2 should be called to free up resources even after sqlite3_open (and family) fails:

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.

This is a bit verbose, because we need to get the message before closing and pass to CHECK_MSG. Alternative would be to keep using CHECK, but then a generic message would be printed.

[flavorjones]

@katafrakt Thanks for the PR. Reading the docs, this does sound like the right thing to do.

Can I ask how you ran into this? Is there an easy way to reproduce the underlying failure conditions? I'd like to try to write a test and run it under valgrind/ASan to make sure memory leaks are all quashed.

[flavorjones]

Ah - ignore my question, I see it's as easy as opening a nonexistent file. I'll try to put a test around this, but the change itself seems fine. Thanks!

Worth noting: in the current codebase the memory is eventually cleaned up when the object is GCed, but this change would make that cleanup happen immediately which is definitely better.