Node.js, caman: Error: Image given has not completed loading only with jpg images

Hy I'm editing various images that are stored locally on my pc, I have no problems with a png images, but when I try editing jpg images I always get the following error

this.context.drawImage(this.image, 0, 0, this.imageWidth(), this.image
                 ^
Error: Image given has not completed loading

here is my code

Caman('C://images//' + req.body['storedName'], function () {
    var regulations = JSON.parse(req.body['regulations']);
    this.saturation(regulations.saturation);
    this.sepia(regulations.sepia);
    this.vibrance(regulations.vibrance);
    this.sharpen(regulations.sharpen);
    this.brightness(regulations.brightness);
    this.contrast(regulations.contrast);
    this.exposure(regulations.exposure);
    this[req.body['preset']]();
    this.render(function () {
        this.save('C://images//' + req.body['storedName']);
    });
});

Any idea what the problem might be? Thanks.

EDIT after @ lombausch comment I changed my code, so now it looks like this,

var myimage = new Canvas.Image();
myimage.onload = function() {
    Caman('C://images//' + req.body['storedName'], function () {
        var regulations = JSON.parse(req.body['regulations']);
        this.saturation(regulations.saturation);
        this.sepia(regulations.sepia);
        this.vibrance(regulations.vibrance);
        this.sharpen(regulations.sharpen);
        this.brightness(regulations.brightness);
        this.contrast(regulations.contrast);
        this.exposure(regulations.exposure);
        this[req.body['preset']]();
        this.render(function () {
            var extension = path.extname(req.body['storedName']);
            var filename = path.basename(req.body['storedName'],extension);
            this.save('C://images//' + filename + '-caman' + extension);
            res.json({ status:'success' });
        });
    });
};
myimage.onerror = function(err){
    console.log(err);
    res.json({status:"error", message:err});
};
myimage.src = 'C://images//' + req.body['storedName'];

the error doosn't show up anymore but nothing happens, and when I say nothing I mean nothing, not an error emssage, nor anything else,seems like the onload never get's fired.