FIX: allow an admin to click on blank errors (#5027)

* FIX: allow an admin to click on blank errors

* i18nlize strings

* what would a rails master do?

app/serializers/incoming_email_serializer.rb

@@ -29,4 +29,8 @@ class IncomingEmailSerializer < ApplicationSerializer
     object.cc_addresses.split(";")
   end
 
+  def error
+    @object.error.presence || I18n.t("emails.incoming.unrecognized_error")
+  end
+
 end