ERROR: Unable to mount SD card : NOT_READY

I am attempting to load and execute a JS file from the SD card.

eval(require('fs').readFile("aes.js"));

The aes.js file is loaded to the root of the SD card. That code produces the error:

ERROR: Unable to mount SD card : NOT_READY

Eventually, I would like to load the aes.js file to execute:

var encrypted = CryptoJS.AES.encrypt("Message", "Secret Passphrase");

    var decrypted = CryptoJS.AES.decrypt(encrypted, "Secret Passphrase");