HTML widget JS: activate

I have a CS form with an HTML widget on it. 

The CS form has a proc on it as per below. 

entry lp_refresh
	$fieldhandle("d_to_do_list")->$widgetoperation("JS:uniface.getInstance('SYD_TO_DO_LIST').activate('refresh')")
end

The DSP SYD_TO_DO_LIST has an operation refresh as per below. Where “widget” is the name of a DSP container widget. 

operation refresh
public web

scope
	input
	output
	operation all_instances().refresh
endscope

	if(widget != "" & widget != "SYD_BI")
		activate widget.refresh()
	endif


	return 0
end

This successfully executes the refresh operation on the DSP contained by the widget container, and in turn on a widget contained by that container. So it all appears good. 

However, if I inspect the cef process (ENABLEDEVTOOLS=true), it builds up uncaught exceptions as per below, every time the refresh is fired. NOTE the refresh works, it just stacks an error in the dev tools. 

VM124:1 Uncaught TypeError: uniface.getInstance(...).activate(...) is not a function at <anonymous>:1:58

with the details given when expanding this as:-

uniface.getInstance('SYD_TO_DO_LIST').activate('refresh')();

So where does the extra () come from? There are no parameters to any refresh operation on any of the contained DSPs.