Fix an issue with `ConduitQueryConduitAPIMethod`

Fixes an issue with D9991. A user was hitting the following exception:

```
echo '{}' | arc --conduit-uri='http://phabricator.joshuaspence.com'
call-conduit conduit.query
Waiting for JSON parameters on stdin...
Exception
[HTTP/500] Internal Server Error
>>> UNRECOVERABLE FATAL ERROR <<<

Call to a member function getAPIMethodName() on a non-object

/usr/src/phabricator/src/applications/conduit/method/ConduitQueryConduitAPIMethod.php:34

┻━┻ ︵ ¯\_(ツ)_/¯ ︵ ┻━┻
(Run with --trace for a full exception trace.)
```

Auditors: epriestley