- Page_layout_problem layout (NULL, SCM_EOL, scm_list_1 (sys->self_scm ()));
-
- layout.solution (true);
+ if (sys)
+ {
+ Page_layout_problem layout (NULL, SCM_EOL, scm_list_1 (sys->self_scm ()));
+ layout.solution (true);
+ }
+ else
+ programming_error ("vertical alignment called before line breaking");