From 28f5805fe528445779e08ab1ea4bebe714df40ba Mon Sep 17 00:00:00 2001
From: Keith OHara <k-ohara5a5a@oco.net>
Date: Wed, 9 Jan 2013 10:32:20 +0100
Subject: [PATCH] Fix assertion failure (#2983).

---
 lily/line-spanner.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lily/line-spanner.cc b/lily/line-spanner.cc
index f80d58132d..936a956008 100644
--- a/lily/line-spanner.cc
+++ b/lily/line-spanner.cc
@@ -189,7 +189,9 @@ Line_spanner::calc_bound_info (SCM smob, Direction dir)
         }
       else
         {
-          y = me->get_bound (dir)->extent (common_y, Y_AXIS).center ();
+          Interval ii = me->get_bound (dir)->extent (common_y, Y_AXIS);
+          if (!ii.is_empty())
+            y = ii.center ();
           details = scm_acons (ly_symbol2scm ("common-Y"), common_y->self_scm (), details);
         }
 
-- 
2.39.2