Javascript Undefined, When I Just Logged It

So I just posted a Q about a nested date object and got a speedy answer, felt kinda silly, it was obvious, but no sooner did I get one correct response when something else throw an

Solution 1:

key seems to be an array.

Get the first entry from that array: key[0]._id

key[0] is:

{"_id":"5a72c5cbe617796370219fb3","key":"mWJhRlytyjaxztWfsP6tpH7PccEpSfkemZqyt9pf26e4fI1b32e5Qun8LfLKmkhXMytFtB7QYHHLUgGV0V7AwUB055Cp78Old2IrBHlmgDDFl6qYxe05cgTFLzjmzuAZ","user_id":"5a72c5cbe617796370219fb2","type":"registration","__v":0,"date":{"redeemed":null,"issued":"2018-02-01T07:46:19.449Z"}}