I am seeing this a lot more these days because of extensions in AX7. You tend to take the form run in the event and try to get a form control.
A lot of developers seem to be hard coding the control name. Not wrong but not the best way to do it. A form control name could change or be deleted. Then you wont catch this until a user runs it.
Not so good way:
The right way:
This way you get your errors during compile time.