broken context when serverOptions.context is set

[irzhywau]

I've tried to add some feature in my app regarding authorization by relying on apollo context which I thought to implement in serverOptions

https://www.apollographql.com/docs/apollo-server/security/authentication/#putting-authenticated-user-info-on-the-context

unfortunately, I got an error Cannot read property 'call' of undefined. https://github.com/moleculerjs/moleculer-apollo-server/blob/master/src/service.js#L246

After a checking I saw that context.ctx is indeed undefined and the whole context object has changed. I can see what I implemented in the step before but none of what should be there