grpc-go: Surface TLS errors to RPC errors

Hello, I was trying to check what error was returned from the server when the client’s certificate is expired. The error I got was generic: transport is closing. At first I was thinking the idea was to not expose the error, for security reasons. However, after some research, I’ve found that the std tls package sends alerts to the client, in that case the alert was: alertBadCertificate. So far so good, but it turned out that the grpc http2 client disregards that alert and does not expose it to the end user. That’s the code where error/alert is disregarded:

// .../google.golang.org/grpc@v1.27.0/internal/transport/http2_client.go:1242

func (t *http2Client) reader() {
	defer close(t.readerDone)
	// Check the validity of server preface.
	frame, err := t.framer.fr.ReadFrame()
	if err != nil {
		t.Close() // this kicks off resetTransport, so must be last before return
		return
	}
	t.conn.SetReadDeadline(time.Time{}) // reset deadline once we get the settings frame (we didn't time out, yay!)
	if t.keepaliveEnabled {
		atomic.StoreInt64(&t.lastRead, time.Now().UnixNano())
	}
	sf, ok := frame.(*http2.SettingsFrame)
	if !ok {
		t.Close() // this kicks off resetTransport, so must be last before return
		return
	}
// ....

After debugging, I’ve found that in that line frame, err := t.framer.fr.ReadFrame() alert is received as error, but not used and just the transport is closed, without any more info. Is that on purpose? If not, I am willing to contribute to the project and fix it.