Fix scratchpad fullscreen behavior and crash

When setting fullscreen on a hidden scratchpad container, there was a
check to see if there was an existing fullscreen container on the
workspace so it could be fullscreen disabled first. Since the workspace
is NULL, it would cause a SIGSEGV. This adds a NULL check to avoid the
crash.

This also changes the behavior of how fullscreen is handled when adding
a container to the scratchpad or changing visibility of a scratchpad
container to match i3's. The behavior is as follows:
- When adding a container to the scratchpad or hiding a container back
  into the scratchpad, there is an implicit fullscreen disable
- When setting fullscreen on a container that is hidden in the
  scratchpad, it will be fullscreen when shown (and fullscreen disabled
  when hidden as stated above)
- When setting fullscreen global on a container that is hidden in the
  scratchpad, it will be shown immediately as fullscreen global. The
  container is not moved to a workspace and remains in the
  scratchpad. The container will be visible until fullscreen disabled
  or killed. Since the container is in the scratchpad, running
  `scratchpad show` or `move container to scratchpad` will have no
  effect

This also changes `container_replace` to transfer fullscreen and
scratchpad status.

1 files changed, 4 insertions, 0 deletions

diff --git a/sway/commands/focus.c b/sway/commands/focus.c
index 14e90955..8baa616d 100644
--- a/sway/commands/focus.c
+++ b/sway/commands/focus.c
@@ -182,6 +182,10 @@ static struct sway_node *node_get_in_direction_floating(
         double closest_distance = DBL_MAX;
         struct sway_container *closest_con = NULL;
 
+        if (!con->workspace) {
+                return NULL;
+        }
+
         for (int i = 0; i < con->workspace->floating->length; i++) {
                 struct sway_container *floater = con->workspace->floating->items[i];
                 if (floater == con) {