Missing stack trace on node.js uncaughtException generated by throw()

I'm trying to catch the stack trace of an node.js uncaughtException and it works fine for different errors but not for throw() statements:

Correct stack trace on exception handling:

$ cat errorFunc.js 
process.on('uncaughtException', function(exception) {
    console.log('uncaughtException occurred: ' + exception.stack);
});
MyError();

$ node errorFunc.js 
    uncaughtException occurred: ReferenceError: MyError is not defined
    at Object.<anonymous> (/home/jolcese/code/WebEnclaves/Server/errorFunc.js:5:1)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
    at node.js:901:3
$

Missing stack trace on exception caused by throw():

$ cat errorThrow.js 
process.on('uncaughtException', function(exception) {
    console.log('uncaughtException occurred: ' + exception.stack);
});
throw('my error');

$ node errorThrow.js 
uncaughtException occurred: undefined
$

Any idea why?

Thanks Jose

Disclaimer: I know that using process.on('uncaughtException') is a very, very bad thing and I will be punished but using domains is not an option in this code.