Error after running the app

[akmalkadi]

Hi,
I followed all the instructions and run the app for the first time by clicking on the icon and it opened a page in chrome asking for logging in. I logged in but first I got an error since the app is still in the testing phase and I am not a tester. So I added my email as a tester and then it allowed me to continue. Finally, I got a message that I am okay to close the web-page. I checked the deepin calendar but I didn't find the events nor the reminders.

I tried again to run the app but using the terminal to see if there is an error. I found the following:

 ./deepin-ext-cal-sync
/home/karim/Apps/deepin-ext-cal-sync
Unhandled exception. System.InvalidOperationException: Nullable object must have a value.
   at deepin_ext_cal_sync.Providers.GoogleCalendarProvider.GetEvents(DateTime startDt, DateTime endDt) in /home/sudip/Documents/Projects/deepin-ext-cal-sync/Providers/GoogleCalendarProvider.cs:line 49
   at deepin_ext_cal_sync.Program.Main(String[] args) in /home/sudip/Documents/Projects/deepin-ext-cal-sync/Program.cs:line 33
   at deepin_ext_cal_sync.Program.<Main>(String[] args)
Aborted

Is there anything I can do to make it run? thanks.