PDOException on install and clear all cache

I can't reproduce the issue. Each time I re-install the module, default rules are created properly in rules_config db table and there are no any error messages.
Did you try it out with latest stable releases of Rules and Entity API modules?

Probably, the error occurs because of comma in the rules config label:
"LABEL" : "Purge Fastly cache when a comment is created, updated or deleted."
but I am not sure since it works fine for me and exported rules have valid json.

  $configs['rules_fastly_purge_comment'] = rules_import('{ "rules_fastly_purge_comment" : {
      "LABEL" : "Purge Fastly cache when a comment is created, updated or deleted.",
      "PLUGIN" : "reaction rule",
      "OWNER" : "rules",
      "TAGS" : [ "fastly" ],
      "REQUIRES" : [ "rules", "fastly", "comment" ],
      "ON" : { "comment_update" : [], "comment_delete" : [], "comment_insert" : [] },
      "DO" : [
        { "fastly_rules_action_purge_by_urls" : { "urls" : "comment\/[comment:cid]\r\nnode\/[comment:node:nid]\r\n[site:url]" } }
      ]
    }
  }');

Hmm ... same happening here. I removed the comma from the labels just to see if that did anything, but the issue remains. I've tried both branches and they have the same issue.

I have also ensured that entity is updated and I even switched to the dev branch of Rules to ensure I had the very latest.

I still get this error message and the cache is not able to clear.

There is only one reason when I can reproduce the issue. This is when the core Comment module is turned off on the site.
Most likely the core Comment module is disabled on your site.
I have added a patch to fix the issue.

It is ... I use a Facebook comment module. I will test this patch. Thank you so much!

This worked beautifully!

Pulled in the patch and tried it out. Works great for me. Out of curiosity at what point should we merge this in?

Patch for #3 commited.
i think we can close this.

Thanks to all