How to write pipeline with group along with match?

I write parse aggregation pipeline using group and match but it doesn’t work It works in mongo compass but it rejects in parse server please suggest correct syntax

test(callback) {
    let Employee = Parse.Object.extend("Employee");
    var query = new Parse.Query(Employee);
    var pipeline = [
        [
            {
                'match': {
                    'isActive': true
                } 
            }, {
                'group': {
                    'objectId': null, 
                    'total': {
                        '$sum': '$defaultAccNum'
                    }
                }
            }
        ]
    ]

    query.aggregate(pipeline, { useMasterKey: true })
        .then(function (results) {
            debugger
            // results contains sum of score field and stores it in results[0].total
          }).catch(function (error) {
            // There was an error.
          });
    }
}

Can you please also share the error stack?