Bugfix/Node.js 18 -> Assertion failed: (object->InternalFieldCount() > 0)

[TheDadi]

This PR fixes the error Assertion failed: (object->InternalFieldCount() > 0) when building with node-canvas with a Node.js version > 18

• Have you updated CHANGELOG.md?

[TheDadi]

@zbjornson I reimplemented everything on the prototype and added some custom checks if the current this is a valid instance of the given constructor since the way you used to prevent the invoke of the accessor on an invalid this, with passing the AccessorSignature to the Nan:SetAccessor is deprecated and was removed in NodeJS 18 as you can see in this commit nodejs/nan@7f9ceb8. https://github.com/nodejs/nan/blob/7f9ceb80fbc45c9ba1a10e6591ccbef9e8dee6b4/nan.h#L2553

[zbjornson]

What a pain to have to do this in every method 🥴 but this looks correct, thank you! Will review closely soon.

[zbjornson]

I read through the V8 change and this indeed seems correct.

Looks good but we can save a lot of lines with a macro (see below). I'm hoping to work on prebuilds this weekend since v18 is becoming LTS soon. If you don't have time, I might make this style change tonight (Pacific) or tomorrow.

Thanks again!

[zbjornson]

We can save quite a few lines of code by doing:

#define CHECK_RECEIVER(prop) \
  if (!Canvas::constructor.Get(info.GetIsolate())->HasInstance(info.This())) {
    Nan::ThrowTypeError("Method " #prop " called on incompatible receiver");
    return;
  }

NAN_GETTER(Canvas::GetType) {
  CHECK_RECEIVER(GetType)
}

[joeyguerra]

Looking forward for this.

[zbjornson]

Thanks again! I'll do the macro change after merging.