Fix the error serialization for the inter-thread messaging (#641)

packages/kernel/src/worker.ts

@@ -472,11 +472,21 @@ self.onmessage = async (event: MessageEvent<InMessage>): Promise<void> => {
   } catch (error) {
     console.error(error);
 
-    // The `error` object may contain non-serializable properties such as function,
+    if (!(error instanceof Error)) {
+      throw error;
+    }
+
+    // The `error` object may contain non-serializable properties such as function (for example Pyodide.FS.ErrnoError which has a `.setErrno` function),
     // so it must be converted to a plain object before sending it to the main thread.
     // Otherwise, the following error will be thrown:
     // `Uncaught (in promise) DOMException: Failed to execute 'postMessage' on 'MessagePort': #<Object> could not be cloned.`
-    const cloneableError = JSON.parse(JSON.stringify(error)); // Ref: https://stackoverflow.com/a/42376465/13103190
+    // Also, the JSON.stringify() and JSON.parse() approach like https://stackoverflow.com/a/42376465/13103190
+    // does not work for Error objects because the Error object is not enumerable.
+    // So we use the following approach to clone the Error object.
+    const cloneableError = new Error(error.message);
+    cloneableError.name = error.name;
+    cloneableError.stack = error.stack;
+
     messagePort.postMessage({
       type: "reply",
       error: cloneableError,