Link fails for directories with "Access violation"

[ncw]

Adding this unit test (in the fix-link-dir branch) shows that Link fails on directories.

func TestExportDir(t *testing.T) {
	session := initSession(t)
	node := createDir(t, session, "testdir1", session.FS.root)

	// Don't include decryption key
	retry(t, "Failed to export link (key not included)", func() error {
		_, err := session.Link(node, false)
		return err
	})

	// Do include decryption key
	retry(t, "Failed to export link (key included)", func() error {
		_, err := session.Link(node, true)
		return err
	})
}

The result of this is

--- FAIL: TestExportDir (2.19s)
	mega_test.go:35: Failed to export link (key not included) failed: Access violation

[ncw]

@sogko you wrote the code for this originally - any ideas?