fix: init after __wasm_call_ctors

[toyobayashi]

Fixes #15

[RReverser]

Wouldn't it be easier to do all this init from C/C++ rather than by dealing with JS helpers?

For example, this callback could be just another __attribute__((constructor)) instead of adding it as a separate init from JS, and then all those surrounding calls would probably be simpler & smaller when express via napi.h too.

[toyobayashi]

This callback will not be called until addRunDependency("emnapi-init") is removed, it's asynchronous

[RReverser]

Hm why? Is there anything in actual N-API that is asynchronous?

[toyobayashi]

emnapi/packages/emnapi/src/init.ts

Lines 117 to 129 in b750157

	$emnapiInit__postset: 'addOnPreRun(function (Module) {' +
	'addRunDependency("emnapi-init");' +
	'emnapiRuntimeInit(Module).then(function () {' +
	'emnapiInit();' +
	'removeRunDependency("emnapi-init");' +
	'}, function (err) {' +
	'if (typeof Module.onEmnapiInitialized === "function") {' +
	'Module.onEmnapiInitialized(err);' +
	'} else {' +
	'throw err;' +
	'}' +
	'});' +
	'});',

emnapi/packages/emnapi/src/init.ts

Line 26 in b750157

$emnapiRuntimeInit: function emnapiRuntimeInit (Module: any) {

emnapiRuntimeInit (async) then emnapiInit (__ATINIT__.push())

[toyobayashi]

emnapiInit depends emnapiRt and emnapiCtx, which is asynchronously initialized in emnapiRuntimeInit

[RReverser]

Hm, but then, C/C++, including __attribute__((constructor)), also won't be called until addRunDependency is removed, so the effect should be the same?

[RReverser]

If not, I probably will need to look a bit deeper later.

[toyobayashi]

But we always need to create Env and export emnapiExport on JavaScript side, current implementation can easily use closure to save variables. (I found out Node.js official node_api.h uses __attribute__((constructor)) only on native platforms, but export napi_register_wasm_v1 on wasm, during initialization the host environment should pass env and export to it.)

https://github.com/nodejs/node/blob/513c15147cb44d2d27073e520820146185c45638/src/node_api.h#L76-L107