Small email fixes

app/mailers/user_notifications.rb

@@ -46,7 +46,7 @@ class UserNotifications < ActionMailer::Base
       @featured_topics, @new_topics = @featured_topics[0..4], @featured_topics[5..-1]
 
       # Sort the new topics by score
-      @new_topics.sort! {|a, b| b.score - a.score } if @new_topics.present?
+      @new_topics.sort! {|a, b| (b.score || 0) - (a.score || 0) } if @new_topics.present?
 
       @markdown_linker = MarkdownLinker.new(Discourse.base_url)
 

lib/email/styles.rb

@@ -28,7 +28,7 @@ module Email
         end
 
         # ensure no schemaless urls
-        if img['src'].starts_with?("//")
+        if img['src'] && img['src'].starts_with?("//")
           img['src'] = "http:" + img['src']
         end
       end