500 Internal Server Error about ocpp-rpc HOT 2 CLOSED

const { RPCServer, createRPCError, RPCClient } = require('ocpp-rpc');

async function main() {

    const server = new RPCServer({
        protocols: ['ocpp1.6'], // server accepts ocpp1.6 subprotocol
        strictMode: true,       // enable strict validation of requests & responses
    });

    server.auth((accept, reject, handshake) => {
        // accept the incoming client
        accept({
            // anything passed to accept() will be attached as a 'session' property of the client.
            sessionId: 'XYZ123'
        });
    });

    server.on('client', async (client) => {
        console.log(`${client.session.sessionId} connected!`); // `XYZ123 connected!`

        // create a specific handler for handling BootNotification requests
        client.handle('BootNotification', ({params}) => {
            console.log(`Server got BootNotification from ${client.identity}:`, params);

            // respond to accept the client
            return {
                status: "Accepted",
                interval: 300,
                currentTime: new Date().toISOString()
            };
        });
        
        // create a specific handler for handling Heartbeat requests
        client.handle('Heartbeat', ({params}) => {
            console.log(`Server got Heartbeat from ${client.identity}:`, params);

            // respond with the server's current time.
            return {
                currentTime: new Date().toISOString()
            };
        });
        
        // create a specific handler for handling StatusNotification requests
        client.handle('StatusNotification', ({params}) => {
            console.log(`Server got StatusNotification from ${client.identity}:`, params);
            return {};
        });

        // create a wildcard handler to handle any RPC method
        client.handle(({method, params}) => {
            // This handler will be called if the incoming method cannot be handled elsewhere.
            console.log(`Server got ${method} from ${client.identity}:`, params);

            // throw an RPC error to inform the server that we don't understand the request.
            throw createRPCError("NotImplemented");
        });
    });

    await server.listen(3000);


    const cli = new RPCClient({
        endpoint: 'ws://localhost:3000', // the OCPP endpoint URL
        identity: 'EXAMPLE',             // the OCPP identity
        protocols: ['ocpp1.6'],          // client understands ocpp1.6 subprotocol
        strictMode: true,                // enable strict validation of requests & responses
    });

    // connect to the OCPP server
    await cli.connect();

    // send a BootNotification request and await the response
    const bootResponse = await cli.call('BootNotification', {
        chargePointVendor: "ocpp-rpc",
        chargePointModel: "ocpp-rpc",
    });

    // check that the server accepted the client
    if (bootResponse.status === 'Accepted') {

        // send a Heartbeat request and await the response
        const heartbeatResponse = await cli.call('Heartbeat', {});
        // read the current server time from the response
        console.log('Server time is:', heartbeatResponse.currentTime);

        // send a StatusNotification request for the controller
        await cli.call('StatusNotification', {
            connectorId: 0,
            errorCode: "NoError",
            status: "Available",
        });
    }
}
main().catch(console.error);