Handle error when "query" is of shape %{opts: opts}. Should fix #250.

[derekkraan]

Here is my commentary from #250, to give some context:

I have looked at the code to try to understand what is going on here. handshake_recv/2 is called like so on line 103: handshake_recv(s, %{opts: opts})
Then on line 171 this %{opts: opts} gets sent to handle_handshake/3 as second parameter.
There are three function heads for handle_handshake/3. As far as I can see it's supposed to come out to the one first one, defined on line 202, but it ends up in the third one, defined on line 231.

This is where I lose the plot a little bit, but the case statement on line 1245 is not set up to handle %{opts: opts}, so it crashes.

I can't tell if it's supposed to get to handle_handshake/3 on line 231. Possibly the answer is yes (?). If it is supposed to be able to get there, then there needs to be a case clause added to abort_statement to handle %{opts: opts} as query.

Please advise if there is any additional cleanup that needs to happen. My gut says that there isn't, but I'm also not very familiar with the mariaex internals.

[coveralls]

Coverage increased (+2.5%) to 86.022% when pulling 09a281d on derekkraan:master into 5f4aa50 on xerions:master.

[coveralls]

Coverage increased (+3.2%) to 86.738% when pulling 578fcd4 on derekkraan:master into 5f4aa50 on xerions:master.

[derekkraan]

I have tried running the tests a couple of times but there is always one test that fails in one of the (26) runs. Perhaps you could rerun just that one test for me @xerions?

[derekkraan]

@fishcakez Could you please take a look at this PR? I believe the impact is rather large; it can bring down an entire application if the database starts to refuse new connections (for whatever reason).