- scm_call_1 (proc, get_outlet ()->self_scm());
-
- Simple_music_iterator::process(m);
+ if (ly_is_procedure (proc))
+ scm_call_1 (proc, get_outlet ()->self_scm ());
+ else
+ get_music ()->origin ()->warning (_ ("\\applycontext argument is not a procedure"));
+
+ Simple_music_iterator::process (m);