randr.c: Fix regression with focusing NULL container

This was introduced in db3b9e41874400958cf85b461a5d1ff04a398fa3 which
removed the NULL check for next.

Fixes #3523.

diff --git a/src/randr.c b/src/randr.c
index c0dec7f68c935fb006b46320e540f5f66319e2df..fb127ab5622f1ada69da11b552a8778735972ec9 100644 (file)
--- a/src/randr.c
+++ b/src/randr.c
@@ -974,10 +974,12 @@ void randr_disable_output(Output *output) {
             }
         }
 
-        /* Restore focus after con_detach / con_attach */
-        DLOG("now focusing next = %p\n", next);
-        con_focus(next);
-        workspace_show(con_get_workspace(next));
+        /* Restore focus after con_detach / con_attach. next can be NULL, see #3523. */
+        if (next) {
+            DLOG("now focusing next = %p\n", next);
+            con_focus(next);
+            workspace_show(con_get_workspace(next));
+        }
 
         /* 3: move the dock clients to the first output */
         Con *child;