fs.exists(path, callback) Deprecated

[nathanparker]

The read_from_file function in helper.js uses a deprecated fs.exists() method before attempting to readFile().

Might be better do something like...

read_from_file: () => {
    fs.open(filename, 'r', (err, fd) => {
        if (err) {
            if (err.code === 'ENOENT') {
                console.error(filename + 'does not exist')
                return
            }
        }
        throw err
    }
    fs.readFile(fd) ...
}