Array of subdocuments in Mongoose

I have two schemas.

FAQ Schema 

const EventFAQSchema = mongoose.Schema({
    question: { type: String, req: true },
    answer: { type: String, req: true }
});

EventSchema 

const EventSchema = mongoose.Schema({
   "title": { type: String },
   "description": { type: String },
   "eventFAQs": [{
       type: FAQSchema,
       default: FAQSchema
    }]
})

I am trying to embed an array of objects of type FAQ. But I get the following error

Undefined type 'undefined' at array 'eventFAQs'

I know I am missing a fundamental concept of array of objects. But I have spent a good deal of time trying to find out the reason and couldn't resolve it myself.

via Giridhar Karnik