Fix focus related crashes

* seat_set_focus_warp lacked a container NULL check
* view mapping code needs to use seat_get_focus_inactive

Also, seat_set_focus_warp triggered the wrong IPC event if focus was a
workspace, which resulted in swaybar not showing the workspace as
active.

sway/input/seat.c

@@ -775,8 +775,12 @@ void seat_set_focus_warp(struct sway_seat *seat,
 		}
 	}
 
+	if (container) {
 		if (container->type == C_VIEW) {
 			ipc_event_window(container, "focus");
+		} else if (container->type == C_WORKSPACE) {
+			ipc_event_workspace(NULL, container, "focus");
+		}
 	}
 
 	seat->has_focus = (container != NULL);

sway/tree/view.c

@@ -496,7 +496,7 @@ static struct sway_container *select_workspace(struct sway_view *view) {
 	}
 
 	// Use the focused workspace
-	ws = seat_get_focus(seat);
+	ws = seat_get_focus_inactive(seat, &root_container);
 	if (ws->type != C_WORKSPACE) {
 		ws = container_parent(ws, C_WORKSPACE);
 	}
@@ -505,7 +505,8 @@ static struct sway_container *select_workspace(struct sway_view *view) {
 
 static bool should_focus(struct sway_view *view) {
 	struct sway_seat *seat = input_manager_current_seat(input_manager);
-	struct sway_container *prev_focus = seat_get_focus(seat);
+	struct sway_container *prev_focus =
+		seat_get_focus_inactive(seat, &root_container);
 	struct sway_container *prev_ws = prev_focus->type == C_WORKSPACE ?
 		prev_focus : container_parent(prev_focus, C_WORKSPACE);
 	struct sway_container *map_ws = container_parent(view->swayc, C_WORKSPACE);