Added module code to Modules cache - but (still) getting 'Module XYZ' not found

The following code works just fine, but provides me twice with a warning Module ABC not found when uploading to the board. Since I provide the module id and code, I would not expect any warnings on .addCached() nor on require().

For 1V71:

Modules.addCached("ABC"
  , "exports.name = 'Espruino'; "
   +"exports.spelled = function() { return exports.name.split('').join(' - '); }; "
  );

var m;
console.log((m = require("ABC")).name); // --> Espruino
console.log(require("ABC").spelled()); // --> E - s - p - r - ...
m.name = "espruino";
console.log(require("ABC").spelled()); // --> e - s - p - r - ...
console.log(m.name); // --> espruino
console.log(m.spelled()); // --> e - s - p - r - ...

Above code proves that repeated require() return the very same module (object).

For *1v72 - which supports generic exports for more obvious object-oriented programming style with singletons and classes defined in/as modules - I use this code, and get the same complaints about Module XYZ not found:

Modules.addCached("XYZ" // Singleton
  , "exports = "
   +"{ name: 'Espruino' "
   +", spelled: function() { "
   +"      return this.name.split('').join(' - '); } "
   +"}; "
  );

console.log(require("XYZ").name); // --> Espruinus
console.log(require("XYZ").spelled()); // --> E - s - p - r - ...
require("XYZ").name = "espruino"; // modifying module / singleton
console.log(require("XYZ").name); // --> espruino
console.log(require("XYZ").spelled()); // --> e - s - p - r - ...

Modules.addCached("Person" // Class
  , "var Person = function(name) { "
   +"    this.name = name; "
   +"  }; "
   +"Person.prototype.spelled = function() { "
   +"    return this.name.split('').join(' - '); }; "
   +"exports = Person; "
 );

// var Person = require("Person");
// var person = new Person("Espruinus");
var person = new (require("Person"))("Espruinus");
console.log(person.name); // --> Espruinus
console.log(person.spelled()); // --> E - s - p - r - ...
person.name = "Scriptus";
console.log(person.spelled()); // --> S - c - r - i - ...
require("Person").prototype.spelled 
  = function() { return this.name.split('').join(' = '); };
console.log(person.spelled()); // --> S = c = r = i = ...