GoLang Sentinel Error Wrapping

The GoLang error model is in my opinion one of the best around. Returning errors is a vast improvement over throwing errors. I won’t go into detail on that, since there are much better write ups about that out there (e.g. The Error Model by Joe Duffy).
There are two main concepts out there when working with errors in Go: [[GoLang Sentinel Errors|Sentinel Errors]] and [[GoLang Error Wrapping|Error Wrapping]]. There are various blog posts on the two topics, even a few by the language mantainers themselves. A very short overview:

• Sentinel Errors are predefined errors that are exported by packages. These error values allow inspecting the returned errors from functions and reacting appropriately to specific kinds of errors.
• Error wrapping adds context to received errors and makes tracing errors sources much easier.

One use case I have not seen much debated though:

// This is an example packages we're using:
var ErrGettingData = errors.New("failed to get data :/")

func GetDataFromSomewhere() data, error {
	// ...
	if /* something went wrong */ {
		return ErrGettingData
	}
	return someData
}

// This is the package we're developing ourselves:
func DoThingsWithData() error {
	data, err := GetDataFromSomewhere()
	if err != nil {
		return fmt.Errorf("failed to get data from somewhere: %w", err)
	}
	// Business logic...
}

If I now want to write tests for DoThingsWithData and check for the kind of error using errors.Is, I can only check for ErrGettingData. I am not able to check for Sentinel Errors that I have defined myself. Or am I?

I propose Sentinel Error Wrapping:

var ErrGettingDataFromSomewhere = errors.New("failed to get data from somewhere")

func DoThingsWithData() error {
	data, err := GetDataFromSomewhere()
	if err != nil {
		returm fmt.Errorf("%w: %w", ErrGettingDataFromSomewhere, err)
	}
	// Business logic...
}

This allows checking with errors.Is for an ErrGettingDataFromSomewhere while still allowing to check for ErrGettingData. Best of both worlds.