FIX: catch nil post earlier, and catch nil custom_fields

plugin.rb

@@ -1,6 +1,6 @@
 # name: post-read-email
 # about: A plugin to give users the option of marking posts as read when emailed
-# version: 0.0.6
+# version: 0.0.7
 # authors: Leo McArdle
 # url: https://github.com/mozilla/discourse-post-read-email
 

plugin_code.rb

@@ -9,9 +9,11 @@ module PostReadEmail
       begin
         return email_log unless SiteSetting.post_read_email_enabled
         return email_log if email_log.kind_of?(SkippedEmailLog)
+        return email_log if email_log.post_id.nil?
+        return email_log unless @user&.custom_fields
         if @user&.custom_fields['mark_post_as_read_on_email'] == 't' ||
            @user&.custom_fields['mark_post_as_read_on_email'] == 'true'
-          post = Post.find(email_log.post_id) unless email_log.post_id.nil?
+          post = Post.find(email_log.post_id)
           if post
             Notification.where(
               user_id: @user.id,