The coins present in the object creation are the ONLY valid coins? Then, what if a test has a credit that includes a non-valid coin? The credit is to be returned in full? An 'insufficient balance' error.

If so, why does the test that goes with this object created:

var vm = new VendingMachine({1:1, 2:0, 4:3, 6:2});

Should an expected result with a non-valid coin 4 - 3 denomination coins)?

Test.assertSimilar(vm.vending(12, {6:4, 3:4}), {3:4, 6:2});

And in the comment below:

Test.assertSimilar(vm.vending(17, {4:4, 2:1}), {}, 'There is no 1 value coins');

It states that there are no 1 value coins, yet in the constructor there are (see above, its in the same block of tests).

You remove the even integers and sum the odd.

[4, 6, 2, 6, 'o', 8, 4, 2, 4] = 0

In [10]: kiyo_lcm_test(a)
[25, 13, 17, 43, 9, 0, 15, 36, 18]
                    ^
                    |
lcm = 0

tip :
"and then empty arrays"

I'm stuck on the same problem. The test expectation wants to give a change total of 30, but your result is giving back 40 in change.
Your issue might be that the state of the coins object goes wrong at some point, but that really depends on how it's implemented...

A coin is considered invalid if the denomination (the key in the object) is not also a key in the coins object when you first instantiate the object.