Filter illegal hexadecimal characters that can be returned from an unnp device.

[DennisCorvers]

No description provided.

[lontivero]

Thanks for the PR. I don't understand what the logger was added for and the try-catch block is not right. However, it seems udp response can contain illegal characters (in this case I see the \x00 but in what part of the message? is it in the end of the response?

[DennisCorvers]

The logger was added to have some additional information when a debugger is not available.

And the try-catch block is right. It returns an empty XmlDocument instead of causing an application crash. The empty document is handled in a different part without causing a crash.

The \x00 occurred at the very start of the message in this case, where a specific device returned an extra header line with non-xml formatted information.