message: change return code
diff: @@ -38,7 +38,7 @@ int perform_lowpass (double *data, int data_len, int sampling_rate, double cutof
  Dsp::Filter *f = NULL;
  if ((order < 1) || (order > MAX_FILTER_ORDER) || (!data))
  {
  - return (int)BrainFlowExitCodes::GENERAL_ERROR;
  + return (int)BrainFlowExitCodes::INVALID_ARGUMENTS_ERROR;
  }
  switch (static_cast<FilterTypes> (filter_type))
  {
  