Error: The server threw an exception

Does anyone know what causes this error "Error: The server threw an exception"? Specifically I am getting this intermittently when calling a function that is in a script extension from my main test framework code. The function that gives this error is calling a method on a Delphi grid. When I've been able to catch this happening in debug, inspecting the grid shows lots of these errors throughout the properties of the component.

Any advice very much appreciated.