handle non strings passed to Page.cname

lib/gollum/page.rb

@@ -202,7 +202,9 @@ module Gollum
     #
     # Returns the String canonical name.
     def self.cname(name)
-      name.gsub(%r{[ /<>]}, '-')
+      name.respond_to?(:gsub)      ?
+        name.gsub(%r{[ /<>]}, '-') :
+        ''
     end
 
     # Convert a format Symbol into an extension String.

test/test_page.rb

@@ -110,4 +110,9 @@ context "Page" do
     footer = @wiki.page("_Footer")
     assert_nil footer.footer
   end
+
+  test "cannot convert non string to human readable page title" do
+    assert_equal '', Gollum::Page.cname(nil)
+    assert_equal '', Gollum::Page.cname(3)
+  end
 end