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, 3 insertions, 6 deletions

diff --git a/sway/desktop/output.c b/sway/desktop/output.c
index 0b3e1edb..b1e3464a 100644
--- a/sway/desktop/output.c
+++ b/sway/desktop/output.c
@@ -251,14 +251,11 @@ static void output_for_each_surface(struct sway_output *output,
         };
 
         struct sway_workspace *workspace = output_get_active_workspace(output);
-        if (!workspace) {
-                return;
-        }
         struct sway_container *fullscreen_con = root->fullscreen_global;
-        if (fullscreen_con && container_is_scratchpad_hidden(fullscreen_con)) {
-                fullscreen_con = NULL;
-        }
         if (!fullscreen_con) {
+                if (!workspace) {
+                        return;
+                }
                 fullscreen_con = workspace->current.fullscreen;
         }
         if (fullscreen_con) {