Add fatal error when port is already in use

Signed-off-by: Hadi <112569860+anotherhadi@users.noreply.github.com>

internal/ui/app/update.go

@@ -107,16 +107,8 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	case proxyPkg.ErrMsg:
 		if msg.Err != nil {
 			log.Printf("proxy error: %v", msg.Err)
-			return m, tea.Batch(
-				func() tea.Msg {
-					return notificationsUI.NotificationMsg{
-						Title: "Proxy Error",
-						Body:  msg.Err.Error(),
-						Kind:  notificationsUI.KindError,
-					}
-				},
-				tea.Quit,
-			)
+			m.fatalErr = msg.Err
+			return m, tea.Quit
 		}
 		return m, nil