Fix for exceptions in Wasm Workers under node

Without this change exceptions thrown in Wasm Workers are lost under
node.

Author: sbc100

src/lib/libwasm_worker.js

@@ -223,7 +223,17 @@ if (ENVIRONMENT_IS_WASM_WORKER
 #if ENVIRONMENT_MAY_BE_NODE
     if (ENVIRONMENT_IS_NODE) {
       /** @suppress {checkTypes} */
-      worker.on('message', (msg) => worker.onmessage({ data: msg }));
+      worker.on('message', (msg) => {
+        if (msg['cmd'] == 'uncaughtException') {
+          // Message handler for Node.js specific out-of-order behavior:
+          // https://github.com/nodejs/node/issues/59617
+          // A worker sent an uncaught exception event. Re-raise it on the main thread.
+          err(`worker sent an error! ${msg.error.message}`);
+          throw msg.error;
+        } else {
+          worker.onmessage({ data: msg });
+        }
+      });
     }
 #endif
 #if RUNTIME_DEBUG

test/test_core.py

@@ -9713,6 +9713,10 @@ def test_wasm_worker_hello(self):
     self.maybe_closure()
     self.do_run_in_out_file_test('wasm_worker/hello_wasm_worker.c', cflags=['-sWASM_WORKERS'])
 
+  @requires_wasm_workers
+  def test_wasm_worker_exceptions(self):
+    self.do_runf('wasm_worker/test_wasm_worker_exceptions.c', 'worker sent an error! Aborted', assert_returncode=NON_ZERO, cflags=['-sWASM_WORKERS'])
+
   @requires_wasm_workers
   def test_wasm_worker_malloc(self):
     self.do_run_in_out_file_test('wasm_worker/malloc_wasm_worker.c', cflags=['-sWASM_WORKERS'])

test/wasm_worker/test_wasm_worker_exceptions.c

@@ -0,0 +1,19 @@
+#include <assert.h>
+#include <stdlib.h>
+
+#include <emscripten/emscripten.h>
+#include <emscripten/console.h>
+#include <emscripten/em_asm.h>
+#include <emscripten/wasm_worker.h>
+
+void do_abort() {
+  emscripten_out("Hello from wasm worker!");
+  abort();
+}
+
+int main() {
+  emscripten_out("in main");
+  emscripten_wasm_worker_post_function_v(emscripten_malloc_wasm_worker(1024), do_abort);
+  emscripten_exit_with_live_runtime();
+  assert(false && "should never get here");
+}