The getQuestionByName() method doesn't return a question instance even though it is returned by the getAllQuestions() method

[JaneSjs]

Please refer to the following demo: View Plunker.
Here is the minimum reproducible JSON:

{
 "pages": [
  {
   "elements": [
    {
     "type": "html",
     "name": "q1"
    }
   ]
  },
  {
   "elements": [
    {
     "type": "text",
     "name": "q2"
    }
   ]
  }
 ],
 "firstPageIsStarted": true,
 "questionsOnPageMode": "questionPerPage",
}