fix: false success in unmount flow

[raj-prince]

Unmount flow started returning false success during the unmount after this.

[gargnitingoogle]

Is it not possible or not desirable to wrap both errors here ? e.g. something like

Suggested change

	return fmt.Errorf("%w: %s", ErrExternallyManagedMountPoint, err)
	return fmt.Errorf("%w: %w", ErrExternallyManagedMountPoint, err)

[raj-prince]

I think, not desirable. Also, Unwrap doesn't work in multi %w scenario - https://go.dev/play/p/3aixFmasPAK

[gargnitingoogle]

In the sample you attached (thanks for it BTW), I see that the errors.Is returns true for both errors on the combined error, but errors.Wrap return nil on it, which is surprizing a bit.

Error: externally managed mount point: EOF
  errors.Is(errWW, ErrExternallyManagedMountPoint): true
  errors.Is(errWW, ErrUnderlying): true
  errors.Unwrap(errWW): <nil>

I am just worried that not wrapping the returned error on the original error would just lose information. There is a way to wrap multiple errors, that can be also be returned using UnWrap e.g. in this sample https://go.dev/play/p/VarDGW6zVe6 , but it's definitely not very easy to use. It returns this:

  errors.Is(errWW, ErrExternallyManagedMountPoint): true
  errors.Is(errWW, ErrUnderlying): true
Unwrapped error 1: externally managed mount point
Unwrapped error 2: EOF