consider QoL changes such as for error handling

[kojq]

• Return appropriate error messages or use exceptions instead of calling quit immediately on errors (e.g., missing config file or insufficient command-line arguments)
• Split the code into separate modules or procedures such as for configuration parsing
• JSON (or another format) validation such as by checking whether mandatory keys exist or if values are of the expected type
• Asynchronous command execution

I don't think logging, unit tests, sanitizing, or automatic generation of documentation will be needed, but we will see.