JSONLoader(), callback called before uv texture image is loaded

I have an object (exported from Blender) which is uv mapped and has a uv texture image. If I use JSONLoader() to load it , the callback function is called before the image is loaded. If I immediately try to render it in the callback, it fails. If I wait few seconds and render it, it works. This fails

var loader = new THREE.JSONLoader(true);
loader.load('Carl.js',
            function ( geometry, materials ) {
                var material = new THREE.MeshFaceMaterial( materials );
                mesh = new THREE.Mesh(geometry, material);
                scene.add(mesh);
                renderer.render(scene, camera);
            }
);

This works

var loader = new THREE.JSONLoader(true);
loader.load('Carl.js',
            function ( geometry, materials ) {
                var material = new THREE.MeshFaceMaterial( materials );
                mesh = new THREE.Mesh(geometry, material);
                scene.add(mesh);
                setTimeout(
                    function(){
                        renderer.render(scene, camera);
                    },
                    2000
                );
            }
);

I took a quick look at the source

JSONLoader calls 
    Loader.initMaterials() which calls
        Loader.createMaterial() which calls
            load_image()

load_image loads image asynchronously. Looks like JSONLoader doesn’t wait on this and calls callback function immediately.

[George35mk]

https://www.youtube.com/watch?v=wkDd-x0EkFU

[pastinepolenta]

@mrdoob any workaround? How can LoadingManager help on this ? Shall I provide a fiddle ? I can reproduce the issue with a 40kb texture on a 3G network