Remove bogus '$this->resource' from SES error handling pathway

Summary: Ref T10728. This property does not exist and is never referenced. The 'resource' key is also never referenced, so I believe this can be safely removed.

Test Plan: Will make @amckinley do my job for me.

Reviewers: chad

Reviewed By: chad

Subscribers: amckinley

Maniphest Tasks: T10728

Differential Revision: https://secure.phabricator.com/D15624