I’m pretty sure I’ve seen this error before. If memory serves me correctly, it occurs when two separate processes are trying to access the radio at the same time. The easiest way to figure out if that is the case would be to reboot the Pi and run the following command:
ps aux | grep ‘rtl_433’ If the output looks similar to the screenshot, your radio has already been claimed by a running process.
If you are going to run any of the test programs make sure you don't have SkyWeather2.py or WeatherSense.py executing. Either one of those will connect to the radio and claim it. If you do have one of them running, stop it before running the test program.