questionGroup.js

const createQuestionGroups = (questionFlow) => {
    const itemTypeQuestion = 'question'
    const itemTypeBranch = 'branch'
  
    const questionGroups = [];
    const itemsCount = questionFlow.length;

    let questionGroupCount = 1;
    let i = 0;

    while (i < itemsCount) {
        let item = questionFlow[i];

        if (item.type ===  itemTypeBranch) {
            const branchDepth = item.depth;
            let itemOrder = 1;
            const questionGroupItems = [];

            while(questionFlow[i+1].type == itemTypeQuestion && questionFlow[i+1].depth == (branchDepth + 1)) {                
                i += 1
                item = questionFlow[i];

                const questionGroupItem = {
                    order: itemOrder, 
                    id: item.id 
                };
                
                questionGroupItems.push(questionGroupItem);
                itemOrder += 1;
                item = questionFlow[i];
            }

            if (questionGroupItems.length > 1) {
                const questionGroup = {
                    title: `Question Group ${questionGroupCount}`,
                    id: uuid(),
                    questions: questionGroupItems,
                };

                questionGroups.push(questionGroup);
                questionGroupCount += 1;
            }
        }

    i += 1;
}

If you are badly worried about it, then see how this looks

while(questionFlow[i+1].type == itemTypeQuestion && questionFlow[i+1].depth == (branchDepth + 1)) {
                i += 1
                item = questionFlow[i];

                const questionGroupItem = {
                    order: itemOrder, 
                    id: item.id 
                };
                
                questionGroupItems.push(questionGroupItem);
                itemOrder += 1;
                item = questionFlow[i];
}

Also edited in the source code - https://gist.github.com/AjithPanneerselvam/c40d2daf36862fc1faabd915d79722ee#file-questiongroup-js-L19