Bug fix for a possible deadlock

If a pcap load is issued while another is in progress, the first pcap
must be stopped. But this callback doesn't close a channel; instead it
adds the close to a callback issued via app.Run. But this can leave the
main select loop blocked in the flow of control from a message on the
operations channel because control will never return to allow the
closure queued up for app.Run to be executed.

ui/ui.go

@@ -1151,8 +1151,8 @@ func (t updatePacketViews) OnClear(closeMe chan<- struct{}) {
 }
 
 func (t updatePacketViews) BeforeBegin(ch chan<- struct{}) {
+	close(ch)
 	ch2 := Loader.PsmlFinishedChan
-
 	t.App.Run(gowid.RunFunction(func(app gowid.IApp) {
 		clearPacketViews(app)
 		t.Ld.Lock()
@@ -1173,8 +1173,6 @@ func (t updatePacketViews) BeforeBegin(ch chan<- struct{}) {
 				time.Duration(2000)*time.Millisecond,
 				10)
 		}, Goroutinewg)
-
-		close(ch)
 	}))
 }