CryptoJS: how to get back a JSON parseable string?

I am trying to encrypt some JSON with simple-crypto-js (which implements crypto-js), then deserialize the decripted text later, but no matter what I try, I always get this error when calling JSON.parse on it:

SyntaxError: Unexpected token o in JSON at position 1

Here's my code:

import SimpleCrypto from "simple-crypto-js"

var crypto = new SimpleCrypto("My key")
var testObject = {  data: "cupcake" }
var stringToEncrypt = JSON.stringify(testObject);
var encryptedString = crypto.encrypt(stringToEncrypt);
console.log("Decrypted text:")
console.log(crypto.decrypt(encryptedString))
console.log();

var tries = [
    ["NO ENCRYPTION     ",stringToEncrypt],   
    ["(plain)           ",crypto.decrypt(encryptedString)],   
    ["as string         ",crypto.decrypt(encryptedString) as string],   
    ["toLocaleString()  ",crypto.decrypt(encryptedString).toLocaleString()],   
    ["toString()        ",crypto.decrypt(encryptedString).toString()],   
    ["toString(8)       ",crypto.decrypt(encryptedString).toString(8)],   
    ["toString(16)      ",crypto.decrypt(encryptedString).toString(16)],   
]

for(let aTry of tries)
{
    try {
        var obj = JSON.parse(aTry[1] as any);
        console.log(`${aTry[0]}:  SUCCESS: ${obj.data}`)
    }
    catch (err)
    {
        console.log(`${aTry[0]}:  FAIL: (string: ${aTry[1]}) ${err.message}`)
    }
}

... which outputs this:

Decrypted text:
{ data: 'cupcake' }

NO ENCRYPTION     :  SUCCESS: cupcake
(plain)           :  FAIL: (string: [object Object]) Unexpected token o in JSON at position 1
as string         :  FAIL: (string: [object Object]) Unexpected token o in JSON at position 1
toLocaleString()  :  FAIL: (string: [object Object]) Unexpected token o in JSON at position 1
toString()        :  FAIL: (string: [object Object]) Unexpected token o in JSON at position 1
toString(8)       :  FAIL: (string: [object Object]) Unexpected token o in JSON at position 1
toString(16)      :  FAIL: (string: [object Object]) Unexpected token o in JSON at position 1