terminal: add missing stop of pool daemon

We forgot to shut down the pool server cleanly when terminating LiT.
While we touch this section of the code we might also shorten it a bit
by using the one line assignment/if construct.

Author: guggero

terminal.go

@@ -423,22 +423,27 @@ func (g *LightningTerminal) shutdown() error {
 	var returnErr error
 
 	if g.faradayStarted {
-		err := g.faradayServer.Stop()
-		if err != nil {
+		if err := g.faradayServer.Stop(); err != nil {
 			log.Errorf("Error stopping faraday: %v", err)
 			returnErr = err
 		}
 	}
 
 	if g.loopStarted {
 		g.loopServer.Stop()
-		err := <-g.loopServer.ErrChan
-		if err != nil {
+		if err := <-g.loopServer.ErrChan; err != nil {
 			log.Errorf("Error stopping loop: %v", err)
 			returnErr = err
 		}
 	}
 
+	if g.poolStarted {
+		if err := g.poolServer.Stop(); err != nil {
+			log.Errorf("Error stopping pool: %v", err)
+			returnErr = err
+		}
+	}
+
 	if g.lndClient != nil {
 		g.lndClient.Close()
 	}