post-save off-USB ESP8266 comms

Have you connected the Huzzah to B6/B7?

It's a common thing with Espruino - the 'console' moves from USB to Serial1 when USB is disconnected - which lets you connect a totally unprogrammed Pico to something like Bluetooth so you can program it.

When it moves, it then stops you reading back data on Serial1. Easy solution is to just put the following right at the top of your code that runs on initialisation:

function onInit() {
  USB.setConsole(); 
  // ...
}

It'll force the console on to USB (even if USB isn't connected)