Webstorm: Memorized getter trickers warning about "read-only property"

Background

When I use a memorized getter like this:

var myModule = {

    get foo () {
        delete this.foo;
        return this.foo = 'something'
    }
};

in Webstorm I receive the warning:

Property is read-only

Question

Why do I get this warning and can I make it disappear?