Don't crash if someone attempts to use an OTF font for a text string.

diff --git a/lily/font-metric.cc b/lily/font-metric.cc
index 2f61d53f3fb821746b6a64e29b98d6a867b1cbdd..655d992123f4859cbc4d73cbdf430d22fbaafc4e 100644 (file)
--- a/lily/font-metric.cc
+++ b/lily/font-metric.cc
@@ -188,7 +188,7 @@ Stencil
 Font_metric::text_stencil (string str) const
 {
   (void) str;
-  assert (false);
+  programming_error("Cannot get a text stencil from this font");
   return Stencil (Box (), SCM_EOL);
 }