Tool crashes when input file extension is not .txt

[SerpentBytes]

Environment Information

Operation System: macOS Monterey
Node version: v16.17.0

Bug Description

The tool crashes when the -i option is used and the source file supplied is not in .txt format

See below:

[Error: ENOTDIR: not a directory, scandir '/Users/taimoordawami/Desktop/Silver Blaze.log'] {
  errno: -20,
  code: 'ENOTDIR',
  syscall: 'scandir',
  path: '/Desktop/Silver Blaze.log'
}

[Myrfion]

fix in #8