fix(dao) auto paging queries not throwing errors in prepare step

Auto paginated aueries that failed preparation used to not throw an
error if the prepare failed. Thus misleading into confusing error
messages as in Kong#532.

kong/dao/cassandra/base_dao.lua

@@ -188,15 +188,19 @@ function BaseDao:_execute(query, args, options, keyspace)
   -- Prepare query and cache the prepared statement for later call
   local statement, cache_key, err = self:get_or_prepare_stmt(session, query)
   if err then
+    if options and options.auto_paging then
+      -- Allow the iteration to run once and thus catch the error
+      return function() return {}, err end
+    end
     return nil, err
   end
 
   if options and options.auto_paging then
-    local _, rows, page, err = session:execute(statement, args, options)
+    local _, rows, err, page = session:execute(statement, args, options)
     for i, row in ipairs(rows) do
       rows[i] = self:_unmarshall(row)
     end
-    return _, rows, page, err
+    return _, rows, err, page
   end
 
   local results, err = session:execute(statement, args, options)