ArduinoUploader NuGet package

I have downloaded the NuGet package Arduino Uploader (https://www.nuget.org/packages/ArduinoUploader/), and receive the following error when trying to run it using the example on the github page (https://github.com/twinearthsoftware/ArduinoSketchUploader) under the .Net package. The code is as follows

var upload = new ArduinoSketchUploader(                new ArduinoSketchUploaderOptions()                    {                    FileName = @"location of the file",                        PortName = "COM7",                    ArduinoModel = ArduinoModel.Micro                    });            upload.UploadSketch();

The error of Exception unhandled occurs on the upload.UploadSketch(); line giving off

ArduinoUploader.ArduinoUploaderException: 'Exception during close of the programmer: 'Object reference not set to an instance of an object.'.'`.The details copied from Visual Studio are `ArduinoUploader.ArduinoUploaderException  HResult=0x80131500  Message=Exception during close of the programmer: 'Object reference not set to an instance of an object.'.  Source=ArduinoUploader  StackTrace:   at ArduinoUploader.BootloaderProgrammers.Protocols.AVR109.Avr109BootloaderProgrammer.Close()   at ArduinoUploader.ArduinoSketchUploader.UploadSketch(IEnumerable`1 hexFileContents)   at ArduinoUploader.ArduinoSketchUploader.UploadSketch()   at arduino_sending_code.Program.Main(String[] args) in C:\Users\User\source\repos\arduino sending code\arduino sending code\Program.cs:line 39  This exception was originally thrown at this call stack:    [External Code]    arduino_sending_code.Program.Main(string[]) in Program.cs

Are there any suggestions to overcome this error?