buster-test returns undefined, when you use not known configuration key

[singles]

This works ok

var config = module.exports;

config["Node tests"] = {
    tests: [
        "test/shared/*-test.js"
    ],
    environment: 'node'
};

but this one ends with returning undefined and no running tests:

var config = module.exports;

config["Node tests"] = {
    tests: [
        "test/shared/*-test.js"
    ],
    foo: "bar"
    environment: 'node'
};

I think, that returned message should be Unknown configuration option 'foo' according to this: https://github.com/busterjs/buster-configuration/blob/master/lib/group.js#L74

[dwittner]

Fixed by 376eb25.