TypeError: cannot read property 'apply' of undefined

[arya6000]

Below is a very simple code that uses rpc.exports

import urllib.request
import os
import time
import frida
import sys
import threading
import traceback


jscode = """

'use strict';

rpc.exports = {
    begin: function (username, password) {
        setImmediate(main(username, password));
        console.log("inside")
    }
};


function main(username, password) {
    console.log("inside main")
}


"""


device = frida.get_usb_device()

package_name = 'com.myapp'
script = None

try:
    device.kill(package_name)
except:
    pass
try:
    os.system("adb shell pm clear " + package_name)
    app = [package_name]
    pid = device.spawn(app)
    time.sleep(5)
    session = device.attach(pid)
    device.resume(pid)


    def on_message(message, data):
        if message['type'] == 'send':
            print(message['payload'])
        elif message['type'] == 'error':
            print(message['stack'])


    script = session.create_script(jscode)
    
    script.on('message', on_message)
    script.load()
    print(script.exports.begin("myusername", "mypassword"))
    #print(script.exports.sub(5, 3))
    print("Done with that begin function")
    time.sleep(45)
    session.detach()
except BaseException as e:
    traceback.print_exc()
    pass


print("DONE")
print("---------------------------------------------")

I get the following error when I run the above script

TypeError: cannot read property 'apply' of undefined
    at [anon] (duk_hobject_props.c:2385)
    at frida/runtime/core.js:57

Is this a bug? or something I am doing wrong?