fix some segfaults

sway/input/seat.c

@@ -94,6 +94,7 @@ static void handle_seat_container_destroy(struct wl_listener *listener,
 
 	// TODO handle workspace switch in the seat?
 	bool set_focus =
+		focus != NULL &&
 		(focus == con || container_has_child(con, focus)) &&
 		con->type != C_WORKSPACE;
 
@@ -103,12 +104,13 @@ static void handle_seat_container_destroy(struct wl_listener *listener,
 		struct sway_container *next_focus = NULL;
 		while (next_focus == NULL) {
 			next_focus = sway_seat_get_focus_by_type(seat, parent, C_VIEW);
-			parent = parent->parent;
 
 			if (next_focus == NULL && parent->type == C_WORKSPACE) {
 				next_focus = parent;
 				break;
 			}
+
+			parent = parent->parent;
 		}
 
 		// the structure change might have caused it to move up to the top of
@@ -440,7 +442,8 @@ struct sway_container *sway_seat_get_focus_by_type(struct sway_seat *seat,
 	wl_list_for_each(current, &seat->focus_stack, link) {
 		parent = current->container->parent;
 
-		if (current->container == container) {
+		if (current->container == container &&
+				(type == C_TYPES || container->type == type)) {
 			return current->container;
 		}
 

sway/tree/container.c

@@ -69,11 +69,11 @@ static struct sway_container *_container_destroy(struct sway_container *cont) {
 	if (cont->children != NULL) {
 		// remove children until there are no more, container_destroy calls
 		// container_remove_child, which removes child from this container
-		while (cont->children->length != 0) {
+		while (cont->children != NULL && cont->children->length != 0) {
-			container_destroy(cont->children->items[0]);
+			struct sway_container *child = cont->children->items[0];
+			container_remove_child(child);
+			container_destroy(child);
 		}
-		list_free(cont->children);
-		cont->children = NULL;
 	}
 	if (cont->marks) {
 		list_foreach(cont->marks, free);
@@ -85,13 +85,17 @@ static struct sway_container *_container_destroy(struct sway_container *cont) {
 	if (cont->name) {
 		free(cont->name);
 	}
+	list_free(cont->children);
+	cont->children = NULL;
 	free(cont);
 	return parent;
 }
 
 struct sway_container *container_destroy(struct sway_container *cont) {
-	cont = _container_destroy(cont);
+	struct sway_container *parent = _container_destroy(cont);
-	return container_reap_empty(cont->parent);
+	parent = container_reap_empty(parent);
+	arrange_windows(&root_container, -1, -1);
+	return parent;
 }
 
 struct sway_container *container_output_create(
@@ -409,7 +413,8 @@ bool find_child_func(struct sway_container *con, void *data) {
 
 bool container_has_child(struct sway_container *con,
 		struct sway_container *child) {
-	if (child->type == C_VIEW || child->children->length == 0) {
+	if (child == NULL || child->type == C_VIEW ||
+			child->children->length == 0) {
 		return false;
 	}
 	return container_find(con, find_child_func, child);

sway/tree/layout.c

@@ -106,11 +106,11 @@ void container_add_child(struct sway_container *parent,
 }
 
 struct sway_container *container_reap_empty(struct sway_container *container) {
-	if (!sway_assert(container, "reaping null container")) {
+	if (container == NULL) {
 		return NULL;
 	}
 	wlr_log(L_DEBUG, "reaping %p %s", container, container->name);
-	while (container != &root_container && container->children->length == 0) {
+	while (container->type != C_VIEW && container != &root_container && container->children->length == 0) {
 		if (container->type == C_WORKSPACE) {
 			if (!workspace_is_visible(container)) {
 				struct sway_container *parent = container->parent;