How to make plugin active without image

[snapzilla]

GIMP 2.10.2 (revision 1)
Windows 10

I have written a plugin in Python that iteratively merges a sequence of image files creating an output image of each iteration.  
 
When I launch GIMP the plugin appears in the menu as expected but it is greyed-out.  If I open an image file the plugin becomes usable.

How do I get GIMP to activate the plugin at launch time without the need to open a random image file?

[Ofnuts]

Just remove the PF_IMAGE parameter (and any PF_DRAWABLE) from the parameters list and set the image type parameter to an empty string.

[snapzilla]

Many thanks.

Had been googling and searching for that fix for days.