wakanda remove() Cannot read property 'remove' of undefined - errCode 4055

I do the tuto wakanda at new version and I have error code 4055 when I play js a method addSuperheroes.js. Please I need help.

Method:

ds.Superhero.remove();
new ds.Superhero({name:"Batman"}).save();
new ds.Superhero({name:"Superman"}).save();
var favoriteSuperhero = new ds.Superhero({name:"Wonder Woman"});
favoriteSuperhero.save();
ds.Superhero.all();

Error:

{
    "__ERROR": [
        {
            "message": "Cannot read property 'remove' of undefined, line #1, file:///Users/arnaudthierard/Documents/Wakanda/solutions/HelloWorldWeb/back-end-superheroes/script/addSuperheroes.js.",
            "componentSignature": "jvsc",
            "errCode": 4055
        },
        {
            "message": "Error evaluating javascript file:///Users/arnaudthierard/Documents/Wakanda/solutions/HelloWorldWeb/back-end-superheroes/script/addSuperheroes.js",
            "componentSignature": "JS4D",
            "errCode": 2
        }
    ]
}

Make sure that the dataclass in the model is named Superhero.( not superhero or SuperHero ... )