FlashApe

Just ran into this one, trying to set parameters that were typed to number to undefined or null. There are a few datatypes you can’t do that with anymore, and Number is ’special’ because they cannot be undefined or null, only NaN. Instead of using Number you can use the special * (untyped) designation, and to test for an undefined Number you can use isNaN().

More info here, here, and here.