Use tblib to pickle errors in `run_in_pyodide`. 
import contextlib
import http.server
import multiprocessing
import os
import pathlib
import queue
import shutil
import socketserver
import sys
import tempfile


@contextlib.contextmanager
def spawn_web_server(dist_dir):

    tmp_dir = tempfile.mkdtemp()
    log_path = pathlib.Path(tmp_dir) / "http-server.log"
    q: multiprocessing.Queue[str] = multiprocessing.Queue()
    p = multiprocessing.Process(target=run_web_server, args=(q, log_path, dist_dir))

    try:
        p.start()
        port = q.get()
        hostname = "127.0.0.1"

        print(
            f"Spawning webserver at http://{hostname}:{port} "
            f"(see logs in {log_path})"
        )
        yield hostname, port, log_path
    finally:
        q.put("TERMINATE")
        p.join()
        shutil.rmtree(tmp_dir)


def run_web_server(q, log_filepath, dist_dir):
    """Start the HTTP web server

    Parameters
    ----------
    q : Queue
      communication queue
    log_path : pathlib.Path
      path to the file where to store the logs
    """

    os.chdir(dist_dir)

    log_fh = log_filepath.open("w", buffering=1)
    sys.stdout = log_fh
    sys.stderr = log_fh

    class Handler(http.server.SimpleHTTPRequestHandler):
        def log_message(self, format_, *args):
            print(
                "[%s] source: %s:%s - %s"
                % (self.log_date_time_string(), *self.client_address, format_ % args)
            )

        def end_headers(self):
            # Enable Cross-Origin Resource Sharing (CORS)
            self.send_header("Access-Control-Allow-Origin", "*")
            super().end_headers()

    with socketserver.TCPServer(("", 0), Handler) as httpd:
        host, port = httpd.server_address
        print(f"Starting webserver at http://{host}:{port}")
        httpd.server_name = "test-server"  # type: ignore[attr-defined]
        httpd.server_port = port  # type: ignore[attr-defined]
        q.put(port)

        def service_actions():
            try:
                if q.get(False) == "TERMINATE":
                    print("Stopping server...")
                    sys.exit(0)
            except queue.Empty:
                pass

        httpd.service_actions = service_actions  # type: ignore[assignment]
        httpd.serve_forever()

import contextlib
import http.server
import multiprocessing
import os
import pathlib
import queue
import shutil
import socketserver
import sys
import tempfile


@contextlib.contextmanager
def spawn_web_server(dist_dir):

    tmp_dir = tempfile.mkdtemp()
    log_path = pathlib.Path(tmp_dir) / "http-server.log"
    q: multiprocessing.Queue[str] = multiprocessing.Queue()
    p = multiprocessing.Process(target=run_web_server, args=(q, log_path, dist_dir))

    try:
        p.start()
        port = q.get()
        hostname = "127.0.0.1"

        print(
            f"Spawning webserver at http://{hostname}:{port} "
            f"(see logs in {log_path})"
        )
        yield hostname, port, log_path
    finally:
        q.put("TERMINATE")
        p.join()
        shutil.rmtree(tmp_dir)


def run_web_server(q, log_filepath, dist_dir):
    """Start the HTTP web server

    Parameters
    ----------
    q : Queue
      communication queue
    log_path : pathlib.Path
      path to the file where to store the logs
    """

    os.chdir(dist_dir)

    log_fh = log_filepath.open("w", buffering=1)
    sys.stdout = log_fh
    sys.stderr = log_fh

    class Handler(http.server.SimpleHTTPRequestHandler):
        def log_message(self, format_, *args):
            print(
                "[%s] source: %s:%s - %s"
                % (self.log_date_time_string(), *self.client_address, format_ % args)
            )

        def end_headers(self):
            # Enable Cross-Origin Resource Sharing (CORS)
            self.send_header("Access-Control-Allow-Origin", "*")
            super().end_headers()

    with socketserver.TCPServer(("", 0), Handler) as httpd:
        host, port = httpd.server_address
        print(f"Starting webserver at http://{host}:{port}")
        httpd.server_name = "test-server"  # type: ignore[attr-defined]
        httpd.server_port = port  # type: ignore[attr-defined]
        q.put(port)

        def service_actions():
            try:
                if q.get(False) == "TERMINATE":
                    print("Stopping server...")
                    sys.exit(0)
            except queue.Empty:
                pass

        httpd.service_actions = service_actions  # type: ignore[assignment]
        httpd.serve_forever()
