Issue #5246: Make empty scores abort engraving process (issue 332470043 by address@hidden)

[beauleetienne0]

Reviewers: ,

Message:
It's a bit odd to announce successful engraving of nothing.

Description:
Issue #5246: Make empty scores abort engraving process

This change makes the "no music" warning fatal during the output
process.

Issue: 5246

Please review this at https://codereview.appspot.com/332470043/

Affected files (+2, -3 lines):
  M lily/global-context-scheme.cc


Index: lily/global-context-scheme.cc
diff --git a/lily/global-context-scheme.cc b/lily/global-context-scheme.cc
index  
a8289d52cf549fcabc63e829ed08b3e7606dd44b..35f26aed7282c721292b9845f8143f3cbd0c9cc4  
100644
--- a/lily/global-context-scheme.cc
+++ b/lily/global-context-scheme.cc
@@ -92,7 +92,7 @@ LY_DEFINE  
(ly_interpret_music_expression, "ly:interpret-music-expression",
   Music *music = unsmob<Music> (mus);
   if (!music)
     {
-      warning (_ ("no music found in score"));
+      error (_ ("no music found in score"));
       return SCM_BOOL_F;
     }

@@ -110,8 +110,7 @@ LY_DEFINE  
(ly_interpret_music_expression, "ly:interpret-music-expression",

   if (!iter->ok ())
     {
-      warning (_ ("no music found in score"));
-      /* todo: should throw exception. */
+      error (_ ("no music found in score"));
       return SCM_BOOL_F;
     }