Default Behaviour for `store.get(undefined)`

[Bug-Reaper]

I've just realized that the default behavior of getting undefined resolves the entire store w/any error or warning. Is an error or warning desirable for case of bad input args?

let u;
let storedu = store.get(u);
console.log(storedu);
// Lists entire contents of the satore

If so, happy to PR.