fs.writeFile() and fs.readFile() not working properly in ESP32

For ESP8266 or ESP32? I'm busy atm, but I'll add some specialized code when I find the time to do so.
If you want to run a web server on the ESP8266: https://github.com/GermanWarez/espruino-esp8266-copy-file-to-storage
It'll stop fs when serving two files in parallel. To prevent this I've implemented a sequential loader in index.html. But if you'd request the page in two browser windows in parallel it'll stop fs. Or if you change index.html to contain e.g. it'll stop fs.
Other ways to stop fs:

• Write to storage first (a lot), then try to copy from storage to fs. A reset between these two operations avoids the stop.
  
• Write to fs often, e.g. 50kB of data in small chunks of 128 bytes.
  It looks like fs needs a lot of RAM, sometimes more than ESP8266 can offer. Storage seems like the better option for ESP8266, and maybe ESP32, too.
  For the ESP32 the limits might be higher, but being from the same family it's very likely to behave similar.