Flash module missing?

Oh - actually forget that. It's not a problem at all.

Basically if you have nothing in FlashEEPROM at that location, f.read will return undefined.

So f.read(0) returns undefined, and E.toString complains because it's given undefined.

Try:

var eepromcontents = f.read(0);
if (eepromcontents!==undefined) {
  var str = E.toString(eepromcontents);
  ...
}

Or make sure you do f.write(0,"Hello") first to put something in there - but personally it'd be good practice to check anyway.