Active file does not persist across refreshes

[nitanagdeote]

https://vizhub.com/nitanagdeote/4f64bfb0bf9449068e6cf5f759c2bfdd?edit=files&file=index.js&tabs=index.js%7Eviz.js

To reproduce:

• Open two files
• Switch between them
• Refresh the page
• Observe that the file open after the refresh is not the same file as was open before the refresh

[curran]

This could be an issue with the way React Router is used.

Potentially related to #495