io/router: don't panic for nil op.Ops arguements to Router.Frame

Fixes gio#306

Signed-off-by: Elias Naur <mail@eliasnaur.com>

io/router/key_test.go

@@ -220,6 +220,11 @@ func TestKeyFocusedInvisible(t *testing.T) {
 
 }
 
+func TestNoOps(t *testing.T) {
+	r := new(Router)
+	r.Frame(nil)
+}
+
 func assertKeyEvent(t *testing.T, events []event.Event, expected bool, expectedInputs ...event.Event) {
 	t.Helper()
 	var evtFocus int

io/router/router.go

@@ -68,13 +68,17 @@ func (q *Router) Events(k event.Tag) []event.Event {
 // Frame replaces the declared handlers from the supplied
 // operation list. The text input state, wakeup time and whether
 // there are active profile handlers is also saved.
-func (q *Router) Frame(ops *op.Ops) {
+func (q *Router) Frame(frame *op.Ops) {
 	q.handlers.Clear()
 	q.wakeup = false
 	for k := range q.profHandlers {
 		delete(q.profHandlers, k)
 	}
-	q.reader.Reset(&ops.Internal)
+	var ops *ops.Ops
+	if frame != nil {
+		ops = &frame.Internal
+	}
+	q.reader.Reset(ops)
 	q.collect()
 
 	q.pointer.queue.Frame(&q.handlers)