Robustify Staff_symbol_referencer::on_line ().

Ensure Staff_symbol::on_line () is called using staff-symbol grob, if present.

diff --git a/lily/staff-symbol-referencer.cc b/lily/staff-symbol-referencer.cc
index dbff0245c609874af177b329914bafcc8d1056d5..4d1c3552c7a7cfceeba41ece0975fd3444c2dff8 100644 (file)
--- a/lily/staff-symbol-referencer.cc
+++ b/lily/staff-symbol-referencer.cc
@@ -35,7 +35,8 @@ Staff_symbol_referencer::on_staff_line (Grob *me)
 bool
 Staff_symbol_referencer::on_line (Grob *me, int pos)
 {
-  return Staff_symbol::on_line (me, pos);
+  Grob *st = get_staff_symbol (me);
+  return st ? Staff_symbol::on_line (st, pos) : false;
 }
 
 bool