Cannot read property 'getCookies' of undefined when using setSharedCookies

1. Follow steps described in Codeceptjs Quickstart to init a new project (installs codeceptjs ~2.6.0).
2. Add custom helper that uses REST helper to make requests and call it in a test.
3. Add setSharedCookies() to config.

> "before all" hook: BeforeSuite for "test something":
> Cannot read property 'getCookies' of undefined

Minimal reproduction is here:
https://github.com/undsoft/codeceptjs-set-shared-cookies-issue