Throw on non-release builds if translating positions on destroyed editor

It’s possible that bundled packages stray into this corner case, so I’d
like us to catch and fix misbehaving packages before exposing users to 
any exceptions. Once we go one release with this turned on, we can
enable the exception for all builds.
Merge pull request #3974 from atom/ns-throw-on-destroyed-editors

Throw on non-release builds if translating positions on destroyed editor