Rollups + loading nodes on demand causes a crash

[matsbryntse]

import '../_shared/shared.js'; // not required, our example styling etc.
import Gantt from '../../lib/Gantt/view/Gantt.js';
import '../../lib/Gantt/feature/Rollups.js';
import ProjectModel from '../../lib/Gantt/model/ProjectModel.js';

const project = new ProjectModel({
    autoLoad  : true,
    transport : {
        load : {
            url : './_dirty1.json'
        }
    },
    taskStore : {
        readUrl : './_dirty2.json'
    }
});

new Gantt({
    appendTo : 'container',
    project,
    features : {
        rollups : true
    },
    columns : [
        { type : 'name', width : 250 }
    ]
});

Rollups.js:189 Uncaught (in promise) TypeError: taskRecord.children.slice is not a function
    at Rollups.onTaskDataGenerated (Rollups.js:189:48)
    at functionChainRunner (InstancePlugin.js:358:31)
    at Gantt.plugInto.<computed> [as onTaskDataGenerated] (InstancePlugin.js:329:49)
    at NewTaskRendering.populateTaskRenderData (NewTaskRendering.js:593:15)
    at NewTaskRendering.renderer (NewTaskRendering.js:688:16)
    at TimeAxisColumn.internalRenderer (TimeAxisColumn.js:346:42)
    at Row.renderCell (Row.js:691:39)
    at Row.render (Row.js:550:23)
    at RowManager.renderFromRow (RowManager.js:939:17)
    at RowManager.reinitialize (RowManager.js:174:12)