I got Dialog undefined. Console Error after Transfer Call using SIP-0.21.2.min.js and

function transferCall(session, transferTarget) {
    console.log("Initiating call transfer...");
    console.log("Session", session);
    console.log("Transfer Target", transferTarget);
    console.log("Session state:", session.state);

    try {
        // Ensure the session is in an established state
        if (session.state !== SIP.SessionState.Established) {
            console.error("Session is not in an established state.");
            return;
        }

        // Ensure the session has a valid dialog
        if (!session._dialog) {
            console.error("Session dialog is undefined.");
            return;
        }

        // Create the target URI for the transfer target
        const targetURI = SIP.UserAgent.makeURI(`sip:${transferTarget}@${session.remoteIdentity.uri.host}`);
        console.log("Target URI:", targetURI);

        if (!targetURI) {
            console.error("Invalid target URI.");
            return;
        }

        // Create a new session for the transfer target
        const newSession = new SIP.Inviter(session.userAgent, targetURI);

        // Options for the refer request
        const transferOptions = {
            requestDelegate: {
                onAccept: function() {
                    console.log("Transfer accepted.");
                    // Handle successful transfer
                    resumeCall(session);
                },
                onReject: function(response) {
                    console.error(`Transfer rejected: ${response.message.reasonPhrase}`);
                }
            }
        };

        // Send the REFER request to transfer the call
        console.log("Sending REFER request to transfer call...");
        session.refer(newSession, transferOptions).catch(function(error) {
            console.error("Failed to send REFER:", error);
        });
    } catch (error) {
        console.error("Exception during call transfer:", error);
    }
}

This is my Transfer function and here session is equal to invitation and transferTarget is Agent Extension number. Need Fix of Dialog undefined error and here I connected Asterisk Server. Here resumeCall(session); is ToggleHoldButtun Function after connected to other agent call will be resumed.