Contact mail action fails
I notice that the first line of your backTrace is line 1190 in the Token.php file, which is this:

   if (empty($contactIDs)) {
      // putting a fatal here so we can track if/when this happens
      CRM_Core_Error::fatal();
    }


Judging from the fact that it appears to happen when you are the only recipient, I'd guess that it's because of something funny about your own contact record. For example - perhaps your contact record (i.e. the one that is connected to your login) is deleted?