Script-Fu script causes error "Unable to run GimpPdbProgress callback" (reproducibility depends on system speed)
I was getting an error "Unable to run GimpPdbProgress callback. The corresponding plug-in may have crashed." when running a script, and distilled it to this minimal repro:
(define (script-fu-debug img drawable dummy) (gimp-display-new (car (gimp-image-new 10 10 RGB))) (gimp-message "message")) (script-fu-register "script-fu-debug" "<Image>/Script-Fu/DEBUG..." "Description" "Author" "License" "2019-01-20" "RGB*, GRAY*, INDEXED*" SF-IMAGE "Image" 0 SF-DRAWABLE "Drawable" 0 SF-STRING "Dummy" "")
Reproducing requires the script to open a GUI, to create a new display and to show a message window after creating the display. Creating a new image is not essential, it's there just to ensure gimp-display-new is called with a valid image.
It doesn't seem related to #1438 (closed) (the only one I found that mentioned the error message). This problem happens on two Linux systems, one with Debian 9.6 self-compiled with Python disabled, and one with Ubuntu 18.04.1 from a PPA. Both use amd64 architecture. Both use GIMP 2.10.4.