PR# 5445 Cannot create delegate for Excel interop callback

This is a follow-up to problem report 5444. It appears to be a separate bug, so I'm submitting a new report.

I've tried to get around Eiffel's inability to create a delegate for Excel interop callbacks by creating the delegate via reflection.

I can't get this to work either. The code below fails with "Object reference not set to an instance of an object" on the indicated line.

Given that $added_new_workbook is not Void, I don't know why this would think there is a null reference.

	added_new_workbook (wb: EXCEL_WORKBOOK) is
		do
			{WINFORMS_MESSAGE_BOX}.show
				("Added workbook", "Hello").do_nothing
		end

	listen_for_added_new_workbook is
			-- Add an event handler for adding a workbook.
		local
			type: SYSTEM_TYPE
			constructors: NATIVE_ARRAY [CONSTRUCTOR_INFO]
			constructor: CONSTRUCTOR_INFO
			args: NATIVE_ARRAY [SYSTEM_OBJECT]
			event: EXCEL_APP_EVENTS_NEW_WORKBOOK_EVENT_HANDLER
		do
			type := {EXCEL_APP_EVENTS_NEW_WORKBOOK_EVENT_HANDLER}
			constructors := type.get_constructors
			check
				constructors.count = 1
			end
			constructor := constructors.item (0)
			check
				constructor.is_public and not constructor.is_static
			end
			create args.make (2)
			args.put (0, Current)
*EXCEPTION -->	args.put (1, $added_new_workbook)
			event ?= constructor.invoke (args)
			excel.add_new_workbook (event)
		end