feat(gui): wait and show fyne-based client error message after the cl…

…ient is started

after the fyne-based client is started, we call api handles.Wait() to wait error and show error
message dialog if there is some error while running (e.g. connection lost or listern port already in
used).
This commit is similar as PR #12. This is for the fyne-based client, while #12 is for swiftui client.

client-ui/main.go

@@ -99,9 +99,11 @@ func main() {
 
 	btnStatus := btnStopped
 	var handles extra.TaskHandles
+	var ignoreWaitErr = true
 	btnStart.OnTapped = func() {
 		if btnStatus == btnRunning { // running can stop
 			btnStatus = btnStopping
+			ignoreWaitErr = true
 			btnStart.SetText("Stopping")
 			handles.NotifyCloseWrapper()
 			btnStart.SetText("Start")
@@ -135,6 +137,17 @@ func main() {
 			}
 			btnStart.SetText("Stop")
 			btnStatus = btnRunning
+			go func() {
+				// the `ignoreWaitErr` the same as swiftui.
+				ignoreWaitErr = false
+				// wait error and stop the client
+				if err := handles.Wait(); err != nil && !ignoreWaitErr {
+					dialog.ShowError(err, w)
+				}
+				btnStart.SetText("Start")
+				btnStatus = btnStopped
+				ignoreWaitErr = true
+			}()
 		}
 	}