From 1afbe9967d561fdcd5784382cac87f67d432a351 Mon Sep 17 00:00:00 2001
From: Parker Moore <parkrmoore@gmail.com>
Date: Sat, 26 Dec 2015 12:23:21 -0500
Subject: [PATCH] document: return nil if bad arg in #<=>

Addresses @envygeek's comment:

https://github.com/jekyll/jekyll/commit/233589e15076c41ac4b95ad6e0595f2f6a4a7ac2#commitcomment-15164178
---
 lib/jekyll/document.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/jekyll/document.rb b/lib/jekyll/document.rb
index 8c1b77cf..14a0a92e 100644
--- a/lib/jekyll/document.rb
+++ b/lib/jekyll/document.rb
@@ -355,7 +355,7 @@ module Jekyll
     # Returns -1, 0, +1 or nil depending on whether this doc's path is less than,
     #   equal or greater than the other doc's path. See String#<=> for more details.
     def <=>(other)
-      return ArgumentError.new("document cannot be compared against #{other}") unless other.respond_to?(:data)
+      return nil unless other.respond_to?(:data)
       cmp = data['date'] <=> other.data['date']
       cmp = path <=> other.path if cmp.nil? || cmp == 0
       cmp