Do not override "interface" in the configuration file

[lonble]

I'm opening this issue because:

• I have found a bug
• I want to request a feature
• I have a question
• Other

I found a strange thing. When running qrcp for the first time, a config.json file is created, which holds the default software configuration. Everything looks normal except interface. interface does not hold the default like other options, but the interface I used the last time I ran qrcp. Every time I switch between ethernet and wifi I get Error: unable to find interface.
I tried setting interface to an empty string and the strange thing happened again. Whatever options are used on the command line will not overwrite the contents of the config.json file, except interface. I can only manually modify config.json every time I switch network environments.
I don't understand why qrcp store the value of interface by default, why overwrite the config file with the interface used the last time I ran qrcp. I think it should rescan available interfaces every time qrcp is run.

[claudiodangelis]

Hey, sorry for the huge delay! Yep, this seems to be a bug. However, I want to change the configuration file format from JSON to YAML in the next release, I will work on this too.

Thanks for reporting!