Test handler definedness in LaTeX::TikZ::Functor

diff --git a/lib/LaTeX/TikZ/Functor.pm b/lib/LaTeX/TikZ/Functor.pm
index e7ee0a60aab9c0a9cd5f63fd9539f2c3bcc82b40..2b6974e995a2854ada2a3714a5d4cf4911f99022 100644 (file)
--- a/lib/LaTeX/TikZ/Functor.pm
+++ b/lib/LaTeX/TikZ/Functor.pm
@@ -60,7 +60,7 @@ BEGIN {
   }
 
   Carp::confess("Invalid handler for target $target")
-                                                  unless ref $handler eq 'CODE';
+                             unless defined $handler and ref $handler eq 'CODE';
 
   return [ $target, $handler, $is_set ];
  });