Fix Stripe.ErrorType.StripeError incorrectly being usable as a runtime class

[xavdid]

Why?

Because of the way our errors were re-exported, Typescript allowed the use of Stripe.ErrorType in runtime code:

// passed `tsc`, but shouldn't:
if (error instanceof Stripe.ErrorType.StripeError) { 
  // ...
}

But at runtime, it would blow up:

16 |   if (error instanceof Stripe.ErrorType.StripeError) {
                                   ^
TypeError: undefined is not an object (evaluating 'Stripe.ErrorType.StripeError')

This was caused by the way we exported ErrorType. It was being described as a class by the type system, but was only usable as a type. To fix, we don't export it as a class in the type system anymore. There's no runtime impact of this, it's purely a types change

Note: I believe we don't need ErrorType any more at all. It was added to work around this bug, but given that .errors now works the way we expect (both as a type and as a value) we can probably drop it in the next major (filed as DEVSDK-3165)

What?

• explicitly export a namespace of errors instead of the runtime module _Error

See Also

• instanceof Stripe.ErrorType.StripeError passes type check but throws at runtime #2661
• DEVSDK-3141

[jar-stripe]

Change looks good. Small bit: the PR description could probably be edited a bit, but otherwise GTG