(process): don't crash if paper == NULL.

diff --git a/lily/book.cc b/lily/book.cc
index 96a66ce00cb0c9ad81b748857b938fb23e4d4507..f007e6263077f88a1e108856f4bc5c38eae98c64 100644 (file)
--- a/lily/book.cc
+++ b/lily/book.cc
@@ -87,7 +87,9 @@ Book::process (Output_def *default_paper,
        return 0;
 
   Output_def *paper = paper_ ? default_paper : paper_;
-
+  if (!paper)
+    return 0;
+  
   Paper_book *paper_book = new Paper_book ();
   Real scale = scm_to_double (paper->c_variable ("outputscale"));
   Output_def *scaled_bookdef = scale_output_def (paper, scale);