Structured errors

A structured error provides contextual information that can be crucial in handling the errors before they reach the user of a program. This recipe shows how such errors can be used.

How to do it...

1. Define a struct containing metadata that captures the error situation.
2. Implement the Error() string method to make it an error.
3. If the error can wrap other errors, include an error or []error to store those.
4. Optionally, implement the Is(error) bool method to control how to compare this error.
5. Optionally, implement Unwrap() error or Unwrap() []error to return wrapped errors.

How it works...

Any data type implementing the error interface (containing only one method, Error() string) can be used as an error. This means that you can create data structures containing detailed error information that can be later acted upon. So, if you need several data fields to describe an error, instead of building an elaborate string and returning it via...