* src/intervals.c (set_intervals_multibyte_1): Fix bug#61887

When `total_length` is 0 there should be no subtree at all, but
`delete_interval` only deletes one interval, so make sure we don't end
up with some stale child of `i`.

src/intervals.c

@@ -2333,6 +2333,9 @@ set_intervals_multibyte_1 (INTERVAL i, bool multi_flag,
 
   if (TOTAL_LENGTH (i) == 0)
     {
+      /* Delete the whole subtree.  */
+      i->left = NULL;
+      i->right = NULL;
       delete_interval (i);
       return;
     }