Scan for nodes doesn't interpret modbus error responses as existent nodes

[Puckfist]

https://github.com/infiniteautomation/modbus4j/blob/master/src/com/serotonin/modbus4j/ModbusMaster.java#L202

The testSlaveNode method catches ModbusTransportException, which is wrapped around timeouts in MessageControl, but it's also possible the device would send an IllegalDataAddressException or IllegalFunctionException while extend ModbusTransportException

Thoughts on if that suggests a slave is indeed at that id?