If your application generates an error while creating a class instance or during a class method call, the current procedure creates an exception.
Microsoft®
Visual Basic® provides an exception handling capability
through the On Error Goto <label> statement,
in which the program execution jumps to <label> when
an error occurs. (<label> must be located
in the same procedure as the On Error Goto statement.)
All errors in Visual Basic are handled this way, including errors
within the MATLAB® code that you have encapsulated into a COM
object. An exception creates a Visual Basic ErrObject object
in the current context in a variable called Err.
See the Microsoft Visual Basic documentation for a detailed discussion on Visual Basic error handling.