input: Don't try to send axis_source when there are no resources

The focus_client pointer may be NULL here if the focused client has no
pointer resources. To avoid a crash, NULL check focus client before
proceeding to send the events.

https://bugs.freedesktop.org/show_bug.cgi?id=94899

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
Reviewed-by: Mike Blumenkrantz <zmike@osg.samsung.com>

src/input.c

@@ -367,6 +367,9 @@ weston_pointer_send_axis_source(struct weston_pointer *pointer, uint32_t source)
 	struct wl_resource *resource;
 	struct wl_list *resource_list;
 
+	if (!pointer->focus_client)
+		return;
+
 	resource_list = &pointer->focus_client->pointer_resources;
 	wl_resource_for_each(resource, resource_list) {
 		if (wl_resource_get_version(resource) >=