Codify nil behavior with test

Author: swanson

test/types/hash_test.rb

@@ -124,4 +124,10 @@ class HashTest < ActiveSupport::TestCase
     @hash = Kredis.hash "myhash", typed: :integer, default: ->() { { space_invaders: "100", pong: "42" } }
     assert_equal({ "space_invaders" => 100, "pong" => 42 }, @hash.to_h)
   end
+
+  test "does not support nil values" do
+    assert_raises do
+      @hash.update("key" => nil)
+    end
+  end
 end