Misleading promise rejection when adding document with `_rev`

[sdvg]

When you try to call hoodie.store.add or hoodie.store.updateOrAdd an a fresh database with a document that contains id and _rev properties, the promise gets rejected with:

Error: Object with id "E06D0AC8-808F-D510-B689-410CFC7A56F0" already exists

While it's okay that the promise gets rejected, the message is misleading and should tell you about the disallowed _rev property.

Code to reproduce:

const remove = () => {
    return hoodie.store.removeAll();
};
const add = () => {
    return hoodie.store.updateOrAdd({"_rev":"2-14a948bba06970abd1a0acea5252c236","id":"E06D0AC8-808F-D510-B689-410CFC7A56F0"});
};
hoodie.ready.then(() => {
    remove()
    .then(add);
});