TypeError: Cannot read property 'root' of undefined

Question

I\'m trying to put a BasicTable function from Material-Ui to my React.js file.
Here is my code.

 import React, { Component } from \'react\';
 import { R         


        

Answer 1

To solve the problem("TypeError: Cannot read property 'root' of undefined "), I revised {} to {} receiving @Nandu Kalidindi advice.
Yeah, I finally could make a table of Material-ui, but another problem came up.
The Nav bar I made has gone to somewhere.

I will attach the picture for it.
[Before fix]

[After solve the Type Error]

Do you guys know why the kind of error happened? How could I solve the error?
I would like to keep use the nav bar after I fix the Type error.