Each child in a list should have unique key prop and my browser router is also undefined

How to clear this problem.
Error in browser router
http://localhost:3000/Questions/undefined and

Each child in a list should have unique key prop.

`

const QuestionList = ({questionsList}) => {
 return (<div>
     {
      questionsList.map((question)=>(
        <Questions question={question} key={question.id}/>
      ))
     }
</div>
</>
 )
}

`

I am trying to build the new component page,i am expected that new component page is created,but as the result is Each child in a list should have unique key prop and my browser router is also undefined.