To make sure the code transferred to the device is received correctly, a Cyclic Redundancy Check can be used on the incoming data. This can be done while receiving the data or before executing the code.
All tinyAVR 1-series and megaAVR 0-series devices have Cyclic Redundancy Check Memory Scan (CRCSCAN) that can be used to verify the Flash content. See AN2521 - CRCSCAN on Devices in the tinyAVR® 1-Series for more info on how to use this peripheral.