Feedback on 'Trigger a flow when a node throws an error'

[asinino]

There is nowhere in the docs a detailed description of the 'error' function API, it is expected to be:

• error(string message, string errorDetails) ?
  or:
• error(string message, object errorDetails) ?

How are this 2 variables handled by the system?

I've searched on:
https://nodered.org/docs/user-guide/handling-errors
and
https://cookbook.nodered.org/basic/trigger-on-error

Is it possible to extend the documentation with the info please?