Invalid callback id received by sendPluginResult - Cordova Plugin iOS - ios

Question

I am trying to implement cordova plugin for ARKit in my ionic app which measures distance between two points. I am able to successfully take the measurements but I am not able to get the measured data back as a result in my ionic app. Below is how my code looks like:
MeasurePlugin+ViewControllerDelegate.swift
extension MeasurePlugin: ViewControllerDelegate {
func allowMultiple() -> Bool {
return allowMultiplePoints ?? false;
}
//Dismiss View
func closeView() {
let data = myViewController.getMeasures();
var result: CDVPluginResult
if (!allowMultiple() && data.count > 0) {
result = CDVPluginResult(status: CDVCommandStatus_OK, messageAs: data[0])
} else {
result = CDVPluginResult(status: CDVCommandStatus_OK, messageAs: data)
}
NSLog(result.message as! String); //getting measured value here
myViewController.view.removeFromSuperview()
self.myViewController = nil
result.setKeepCallbackAs(true)
commandDelegate!.send(result, callbackId: finishListenerCallbackId)
}
#objc func setFinishListener(_ command: CDVInvokedUrlCommand) {
finishListenerCallbackId = command.callbackId
}
}
My www/cordova-plugin-measure.js file looks like:
var exec = require('cordova/exec');
var pluginName = 'MeasurePlugin';
/**
* Callback when the view is dismissed
*/
exports.onFinish = function (success = function(){
console.log("OnFinish Success");
}, error = function(){}) {
exec(success, error, pluginName, 'setFinishListener');
};
So when i try to dismiss the view by calling closeView() function, I am getting error in xcode as "Invalid callback id received by sendPluginResult". Please note, I do get my measure value inside result (notice NSLog(result.message as! String); code) but it is not sending that value back to my ionic component. Any idea what am I doing wrong here?