This may or may not be considered a bug:
tpp_LoRa::sendCommand() tests for the response "+ERR" to determine if the LoRa module responded correctly or not to the previous "AT" command. However, there are error conditions that do not respond with "+ERR"; for example if the LoRa bad rate is set wrong so that the command and the response are meaningless. The test should probably be logically inverted for the correct response of "+OK". If the "+OK" is not received, then the command did not take and there is a problem in communicating with the LoRa module.
This may or may not be considered a bug:
tpp_LoRa::sendCommand() tests for the response "+ERR" to determine if the LoRa module responded correctly or not to the previous "AT" command. However, there are error conditions that do not respond with "+ERR"; for example if the LoRa bad rate is set wrong so that the command and the response are meaningless. The test should probably be logically inverted for the correct response of "+OK". If the "+OK" is not received, then the command did not take and there is a problem in communicating with the LoRa module.