Error handling in go

All go errors should be wrapped using the standard errors package. It has been drastically improved in go version 1.13, therefore we should adhere to the standard.

The current codebase is still full of the github.com/pkg/errors uses, so these need to be slowly replaced by the errors package. All new development should adhere to this standard and use the errors package.

To add context to errors, use: fmt.Errorf("my context: %w", err)

To check if an underlying error corresponds to an expected error, use .Is():

var ErrExplosions = errors.New("Explosions")
...

if errors.Is(err, ErrExplosions) {
    // The underlying error is explosions
}

You can also use a custom error struct, with added context. To make casting easier, we have the .As():

type MyCustomError struct {
    Data string
}

func (mce MyCustomError) Error() string {
    return "I'm very custom"
}
...

mce := MyCustomError{}
ok := errors.As(err, &mce)
if ok {
    // we should be able to access mce.Data here now
}

For more on the improved error context mechanics, read the official blog