https://go.dev/blog/go1.13-errors
https://pkg.go.dev/errors#As

Don’t:

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func isPairingNotFound(err error) bool {
	return err.(errors.Error).ErrorCode() == errors.ErrCodeRegisterPairingNotFound.Code()
}

Do:

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import (
	"errors"
)

func isPairingNotFound(err error) bool {
  var serviceErr service.Error
  if errors.As(err, &serviceErr) {
    return serviceErr.ErrorCode() == errors.ErrCodeRegisterPairingNotFound.Code()
  }
}

The Unwrap, Is and As functions work on errors that may wrap other errors. An error wraps another error if its type has the method Unwrap() error
If e.Unwrap() returns a non-nil error w, then we say that e wraps w.