               func.apply device, args
             , interval
             )
+          else
+            throw new Error 'Missing or invalid interval parameter'
 
         ###
           Normalize a given value to match the given lowerRange and

          is called after 'interval' milliseconds. Repeated call will
          remove any previous schedule.
          @param {Function} func - update function to be called
          @param {Number} interval - interval in milliseconds
          @param [...] - additional parameters which are passed through
                         to the function specified by func once the
                         timer expires

        scheduleUpdate: (func, interval) ->
          members.cancelUpdate()

          if (typeof func is 'undefined')
            throw new Error "Missing function parameter"
          if interval > 0
            members.debug "Next Request in #{interval} ms"
            args = Array.prototype.splice.call arguments, 2
