Steal errors contain a cycle, breaking Feathers error handling

[nlundquist]

If Steal produces an error during an SSR render, Feathers will try to serialize it as part of it's error handling, this will fail since the Steal error contains a cycle. This effectively blocks the error you need to know about behind a useless serialization error.

This Feathers serialization occurs here: https://github.com/feathersjs/feathers/blob/4e4d10a4531db1b69ee1ea7e0df8c199a98b6f49/packages/errors/lib/index.js#L28 after being called here: https://github.com/feathersjs/feathers/blob/1c5c0d3539b1ea04d523e9d3137e2d681f45e0f4/packages/express/lib/error-handler.js#L40-L42

The error being serialized (produced by Steal) includes a cycle shaped like the following:

thisError = {
    message: ...
    errors: [ thisError ]
    ...
}

This is easily reproduced in @MarcGoddard's test app: https://github.com/MarcGodard/site-template

1. Install the dependencies of the app above
2. Remove "moment" from client/node_modules
3. Run mongodb server as per readme
4. Run app via "npm run dev"
5. Load "localhost:8080"

At this point the app will try to SSR render the page, failing due to the missing moment dependency, but the error printed will be a JSON serialization failure due to cycle in the underlying Steal error.

[matthewp]

Do you know where the error in Steal is produced? We could maybe implement toJSON() or something...

[MarcGodard]

Thanks @nlundquist

If anyone needs access to the private repo mentioned, let me know.

[m-mujica]

closing this one since steal is not adding the cycle.

[MarcGodard]

@m-mujica could you help me with suggesting what should be my next step? I think the problem is in can-connect-feathers because it includes the feathers-errors package which no longer is used.

[m-mujica]

@MarcGodard I moved this issue to can-zone where the bug has to be fixed. I sent a PR https://github.com/canjs/can-zone/pull/194.. Once I figure out what's breaking the build, we'll merge and release it. Once it's out I'll let you know so you can test it in your repo.