Avoid rare segfaults in 'check_matrix_pointers'

* src/dispnew.c (check_window_matrix_pointers): No-op if the
window's frame not ready yet.  (Bug#77200)

1 files changed, 13 insertions, 9 deletions

diff --git a/src/dispnew.c b/src/dispnew.c
index 6365dcb9c4d..6cd41620b57 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -3113,18 +3113,22 @@ mirror_line_dance (struct window *w, int unchanged_at_top, int nlines, int *copy
 static void
 check_window_matrix_pointers (struct window *w)
 {
-  while (w)
+  struct frame *f = XFRAME (w->frame);
+
+  if (f->after_make_frame)
     {
-      if (WINDOWP (w->contents))
-        check_window_matrix_pointers (XWINDOW (w->contents));
-      else
+      while (w)
         {
-          struct frame *f = XFRAME (w->frame);
-          check_matrix_pointers (w->desired_matrix, f->desired_matrix);
-          check_matrix_pointers (w->current_matrix, f->current_matrix);
-        }
+          if (WINDOWP (w->contents))
+            check_window_matrix_pointers (XWINDOW (w->contents));
+          else
+            {
+              check_matrix_pointers (w->desired_matrix, f->desired_matrix);
+              check_matrix_pointers (w->current_matrix, f->current_matrix);
+            }
 
-      w = NILP (w->next) ? 0 : XWINDOW (w->next);
+          w = NILP (w->next) ? 0 : XWINDOW (w->next);
+        }
     }
 }