What seems to be the problem in my Datatype?

I got this error message when I only typed nearly 60 characters with gallery “Vendor”.
And also this message “Unhandled exception has occurred in your application.
I have no idea why is this happening to me since I set Datatype to varchar(100). Then I had it change again, set to varchar(MAX) but it did not fix the problem.
May I ask some help from you guys?
Thank you in advance!

[Beta] U@bviews
Unhandled exception has occurred in your application. If you click Continue, the application will ignore this error and attempt to continue. If you click Quit, the application will close immediately.
Object reference not set to an instance of an object.
Details Continue Quit
