Exception when moving record with empty group value

Steps to Reproduce:

Apply the provided code snippet to group the grid by the 'food' column.
Clear foods value for any of the records to create empty group
Drag row from empty group to any other group, see exception raised

const grid = new Grid({
    appendTo : targetElement,

// makes grid as high as it needs to be to fit rows
autoHeight : true,

features : {
    rowReorder: { showGrip: true }
},

store : {
    fields : [
        'name',
        { name : 'foods', type : 'array' },
        'city'
    ]
},

data : [
    {
        id    : 1,
        name  : 'Bruce Wayne',
        foods : ['Pizza', 'Sushi', 'Burgers'],
        city  : 'Gotham'
    },
    {
        id    : 2,
        name  : 'Clark Kent',
        foods : ['Pizza', 'Burgers'],
        city  : 'Metropolis'
    },
    {
        id    : 3,
        name  : 'Barry Allen',
        foods : ['Pizza', 'Sushi'],
        city  : 'Central City'
    },
    {
        id    : 4,
        name  : 'Diana Prince',
        foods : ['Burgers', 'Sushi'],
        city  : 'Themyscira'
    }
],

columns : [
    { field : 'name', text : 'Name', flex : 1 },
    {
        field    : 'foods',
        text     : 'Favorite foods',
        flex     : 1,
        renderer : ({ record, value }) => {
            if (record.isGroupHeader) {
                return value;
            }
            return value?.join?.(', ') ?? '';
        }
    },
    { field : 'city', text : 'City', flex : 1 }
]
});

bryntum / support

Exception when moving record with empty group value #9988