no, you need to throw an instance of a "real" class. One extending Error (I'll add a note in the description)

Hi, in what language? JS? In what test or part of the test suite is it exactly?

EDIT: sure you're actually throwing an exception and not just a string? The code for this test is:

    try {
        m.unlock()
    }
    catch (e) {
        hasThrow = e instanceof EmptyMolecule
        if (!hasThrow) exp = e
    }