multierr package

The multierr package is not a standard Go library; you likely need errors.Join from the standard errors package to combine multiple errors. Use errors.Join to aggregate errors, then check them with errors.Is or errors.As.

import "errors"

err1 := errors.New("first error")
err2 := errors.New("second error")
combined := errors.Join(err1, err2)

if errors.Is(combined, err1) {
    // handle specific error
}

If you specifically need the third-party github.com/hashicorp/go-multierr package, install it with go get github.com/hashicorp/go-multierr and use multierr.Append to combine errors.

The multierr package lets you bundle several errors into one single error object instead of returning just the first one. It matters because it preserves all the context about what went wrong during a complex operation, rather than hiding failures. Think of it like a shopping receipt that lists every item you bought, instead of just showing the total price.