plug in bump map: Works manually, but not using a Python procedure

[Kevin]

Here's a curious thing. The following script-fu works for me using GIMP 2.10.20 on Windows 10

Code:

(define this_menu "<Image>/Quick")

(define    (script-fu_kp24_bump_map image drawable bump_map)
  ;; Start undo group.
  (gimp-image-undo-group-start image)

  (let* (
          (selection (car (gimp-image-get-selection image)))
          (vectors 0)
        )

    (plug-in-bump-map RUN-NONINTERACTIVE image drawable bump_map 135 45 3 0 0 0.0 0 0 0 0)
    
    ;; Flush display.
    (gimp-displays-flush)

    ;; End undo group.
    (gimp-image-undo-group-end image)
  )
)

(script-fu-register "script-fu_kp24_bump_map"
                    _"Bump Map..."
                    "Bump Map"
                    "Me"
                    "Me"
                    "24.3.2015"
                    "*"
                    SF-IMAGE        "Image"        0
                    SF-DRAWABLE         "Drawable"      0
                    SF-DRAWABLE         "Bump-Map"      0
                    )
(script-fu-menu-register "script-fu_kp24_bump_map" this_menu)

It's got some unnecessary code as I took an existing script as a template for speed of prototyping.