From 0912f6869b1b8f3116b3540958a395b96d8909d0 Mon Sep 17 00:00:00 2001
From: Dylan Thacker-Smith <Dylan.Smith@shopify.com>
Date: Thu, 16 Sep 2021 18:46:07 -0400
Subject: [PATCH] Fix some internal errors in filters from invalid input.

These fixes came from improving the corresponding test, so these might not
actually be causing problems in practice.
---
 History.md                               |  6 +++
 lib/liquid/standardfilters.rb            | 48 ++++++++++++++++--------
 test/integration/standard_filter_test.rb | 23 +++++-------
 3 files changed, 48 insertions(+), 29 deletions(-)

diff --git a/lib/liquid/standardfilters.rb b/lib/liquid/standardfilters.rb
index e7cb5c382..98e38f5f4 100644
--- a/lib/liquid/standardfilters.rb
+++ b/lib/liquid/standardfilters.rb
@@ -486,10 +498,16 @@ def apply_operation(input, operand, operation)
     end
 
     def nil_safe_compare(a, b)
-      if !a.nil? && !b.nil?
-        a <=> b
+      result = a <=> b
+
+      if result
+        result
+      elsif a.nil?
+        1
+      elsif b.nil?
+        -1
       else
-        a.nil? ? 1 : -1
+        raise Liquid::ArgumentError, "cannot sort values of incompatible types"
       end
     end
 
diff --git a/test/integration/standard_filter_test.rb b/test/integration/standard_filter_test.rb
index f80d7ad0b..e7b34c164 100644
--- a/test/integration/standard_filter_test.rb
+++ b/test/integration/standard_filter_test.rb
@@ -259,8 +259,8 @@ def test_sort_when_property_is_sometimes_missing_puts_nils_last
       { "price" => 1, "handle" => "gamma" },
       { "price" => 2, "handle" => "epsilon" },
       { "price" => 4, "handle" => "alpha" },
-      { "handle" => "delta" },
-      { "handle" => "beta" }
+      { "handle" => "beta" },
+      { "handle" => "delta" }
     ]
     assert_equal expectation, @filters.sort(input, "price")
   end