How to get SQLSTATE in bookshelf.js?

问题

How does one detect the type of an error that occurs in bookshelf.js when talking to PostgreSQL (or another RDBMS)?

Prompted by this question; I don't use bookshelf.js myself.

A search of the manual did not reveal much that was enlightening.

来源：https://stackoverflow.com/questions/43827704/how-to-get-sqlstate-in-bookshelf-js