Populate a flutter DataTable with data from Firestore using a StreamBuilder

I am attempting to use a StreamBuilder in Flutter to dynamically populate a DataTable using data in Firestore. A similar quesiton was asked by Gustavo which was helpful, but I still can't seem to get my code to work.

The error I receive is 'package:flutter/src/material/data_table.dart': Failed assertion: line 429 pos 15: '!rows.any((DataRow row) => row.cells.length != columns.length)': is not true. This error is obviously indicating that my DataTable seems to have an incongruent number of cells and columns, but I can't see why this is the case because I have used three of each.

Here is my code:

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';

class SkillsMatrixOverall extends StatefulWidget {
  @override
  _SkillsMatrixOverallState createState() => _SkillsMatrixOverallState();
}

@override
class _SkillsMatrixOverallState extends State<SkillsMatrixOverall> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Baby Name Votes')),
      body: new StreamBuilder(
        stream: FirebaseFirestore.instance.collection('baby').snapshots(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) return new Text('Loading...');
          return new DataTable(
            columns: <DataColumn>[
              new DataColumn(
                label: Text('Suggestions'),
              ),
              new DataColumn(label: Text('Name')),
              new DataColumn(label: Text('Votes')),
              new DataColumn(label: Text('Rapper name')),
            ],
            rows: _createRows(snapshot.data),
          );
        },
      ),
    );
  }

  List<DataRow> _createRows(QuerySnapshot snapshot) {
    List<DataRow> newList =
        snapshot.docs.map((DocumentSnapshot documentSnapshot) {
      return new DataRow(cells: [
        DataCell(Text(documentSnapshot.data()['Name'].toString())),
        DataCell(Text(documentSnapshot.data()['Votes'].toString())),
        DataCell(Text(documentSnapshot.data()['Rapper name'].toString())),
      ]);
    }).toList();

    return newList;
  }
}

Thank in advance for your advice!