chore: send errors to stderr

[iffse]

Context.

framework_tool uses both stdout and stderr. But the former one is being overused, having most of the error messages which should be sent to stderr.

This PR only changed print statements which should go to stderr.

[JohnAZoidberg]

In general this is not a bad idea. But I wonder how you noticed it.
The commands don't really return machine readable output. We're you trying to separate stdout and stdin on purpose?

[iffse]

But I wonder how you noticed it.

Fairly noticeable when using along other tools.

The commands don't really return machine readable output. We're you trying to separate stdout and stdin on purpose?

You might be referring to stdout and stderr. They should be separated as convention. For example, if you want to save the device information you can just redirect the stdout output to a file, while keeping the errors in the console. Sending what gone wrong to the file while only printing there was an error in the console doesn't make much sense.