Burp highlight.. and Ctrl-U ..to url encode a section!
Spider
Wont find hidden pages, but will pull obscure/linked ones
Target > Site Map > Spider This Host
app.js ..send to repeater
../partials/admin.html ..found: Download-Backups
../api/users ..found: password/hashes on page
burp > discovery > Copy User-Agent String
gobuster -u http://$IP:3000 -w medium.txt
-a 'Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0'
.. still no help