espnow doesn't give correct error messages

[floitsch]

I got the following error message.

******************************************************************************
Decoding by `jag`, device has version <2.0.0-alpha.81.18+floitsch-espnow-rate.f71e3e98>
******************************************************************************
EXCEPTION error. 
UNKNOWN ERROR 0x5(5)
  0: espnow_send_              <sdk>/esp32/espnow.toit:138:3
  1: Service.send              <sdk>/esp32/espnow.toit:119:5
  2: espnow_tx_task            espnow1.toit:24:13
  3: main.<lambda>             espnow1.toit:17:10
******************************************************************************

That error comes from (where EIO is set to 0x05):

return Primitive::os_error(EIO, process);

full function

PRIMITIVE(send) {
  ARGS(Blob, mac, Blob, data, bool, wait);

  // Reset the value of semaphore(max value is 1) to 0, so no need to check the result.
  xSemaphoreTake(tx_sem, 0);

  esp_err_t err = esp_now_send(mac.address(), data.address(), data.length());
  if (err != ESP_OK) return Primitive::os_error(err, process);

  if (wait) {
    portBASE_TYPE ret = xSemaphoreTake(tx_sem, pdMS_TO_TICKS(ESPNOW_TX_WAIT_US));
    if (ret != pdTRUE) {
      return Primitive::os_error(ETIMEDOUT, process);
    } else {
      if (tx_status != ESP_NOW_SEND_SUCCESS) {
        return Primitive::os_error(EIO, process);
      }
    }
  }

  return Smi::from(0);
}