Hello,
I think i have found a bug about routing/jquery, to reproduce it you can for example replace this line:

<Route path="/add-listing" component={AddListing} />

by this:

<Route path="/listings/new" component={AddListing} />

So if you try to access the page directyly by going to http://localhost:3000/listings/new you'll get this error:
TypeError: Cannot read property 'fn' of undefined

But if you access it through a redirect(navbar for example) then it will work.

If you have any idea about the issue, please let me knwo!

thank you so much, great work!