"error": {
        "driver": true,
        "name": "MongoError",
        "index": 0,
        "code": 11000,
        "errmsg": "E11000 duplicate key error collection: todo.users index: username_1 dup key: { : "sak" }"
    }

"error": {
    "driver": true,
    "name": "MongoError",
    "index": 0,
    "code": 11000,
    "errmsg": "E11000 duplicate key error collection: todo.users index: email_1 dup key: { : "sachin121@gmail.com" }"
}

const UserSchema = new mongoose.Schema(
    {
        email: {
            type: String,
            lowercase: true,
            trim: true,
            index: true,
            unique: true,
            required: true
        },
        username: {
            type: String,
            lowercase: true,
            trim: true,
            index: true,
            unique: true,
            required: true
        },
        password: {
            type: String,
            required: true,
            bcrypt: true
        },
        name: {
            type: String,
            trim: true,
            required: true
        }
    });