Don't crash on a pending spanner in Staff_symbol_engraver dtor.

diff --git a/lily/staff-symbol-engraver.cc b/lily/staff-symbol-engraver.cc
index e5d981b04e28230e39a392b266d9aceb9284b49f..55e118245f2c793ac5b2ff92e995595e639d586e 100644 (file)
--- a/lily/staff-symbol-engraver.cc
+++ b/lily/staff-symbol-engraver.cc
@@ -50,7 +50,11 @@ protected:
 
 Staff_symbol_engraver::~Staff_symbol_engraver ()
 {
-  assert (!span_);
+  if (span_)
+    {
+      // Somehow finalize() was not called?
+      programming_error ("Have a pending spanner in destructor.");
+    }
 }
 
 Staff_symbol_engraver::Staff_symbol_engraver ()