Improve support for reloading module in multiple workers (#402)

* fix: use `NODE_MODULE_INIT` macro to improve worker support

* test: add regression test

* fix(test): skip test on windows, since it actually unloads the module (unlike linux) and segfaults

src/module/isolate.cc

@@ -131,4 +131,6 @@ void init(Local<Object> target) {
 
 } // namespace ivm
 
-NODE_MODULE_CONTEXT_AWARE(isolated_vm, ivm::init) // NOLINT
+NODE_MODULE_INIT(/* exports, module, context */) {
+	ivm::init(exports);
+}

tests/worker-reload.js

@@ -0,0 +1,18 @@
+const { Worker } = require('worker_threads');
+
+if (process.platform === 'win32') {
+    // unloading the module segfaults on Windows, skip for now
+    console.log('pass');
+	process.exit();
+}
+
+(async function () {
+    for (let i = 0; i < 2; i++) {
+        const worker = new Worker("require('isolated-vm')", { eval: true });
+        await new Promise((resolve, reject) => {
+            worker.on('exit', code => code ? reject(new Error(`Worker exited with code: ${code}`)) : resolve());
+            worker.on('error', error => reject(error));
+        });
+    }
+    console.log('pass')
+})().catch(console.error);