focus: add a NULL check in `focus <direction>`

container is checked for NULL in other conditions earlier, it's not
obvious that it can't be undefined here.

1 files changed, 3 insertions, 0 deletions

diff --git a/sway/commands/focus.c b/sway/commands/focus.c
index 99c7e61e..844d1293 100644
--- a/sway/commands/focus.c
+++ b/sway/commands/focus.c
@@ -414,6 +414,9 @@ struct cmd_results *cmd_focus(int argc, char **argv) {
                 return cmd_results_new(CMD_SUCCESS, NULL);
         }
 
+        if (!sway_assert(container, "Expected container to be non null")) {
+                return cmd_results_new(CMD_FAILURE, "");
+        }
         struct sway_node *next_focus = NULL;
         if (container_is_floating(container)) {
                 next_focus = node_get_in_direction_floating(container, seat, direction);