fix tag count validator

lib/diaspora_federation/validators/rules/tag_count.rb

@@ -20,7 +20,7 @@ module Validation
       end
 
       def valid_value?(value)
-        value.count("#") <= params[:maximum]
+        value.nil? || value.count("#") <= params[:maximum]
       end
     end
   end

spec/lib/diaspora_federation/validators/rules/tag_count_spec.rb

@@ -41,5 +41,13 @@ describe Validation::Rule::TagCount do
       expect(validator).not_to be_valid
       expect(validator.errors).to include(:tags)
     end
+
+    it "validates if tags are nil" do
+      validator = Validation::Validator.new(OpenStruct.new(tags: nil))
+      validator.rule(:tags, tag_count: {maximum: 5})
+
+      expect(validator).to be_valid
+      expect(validator.errors).to be_empty
+    end
   end
 end