Conditions under which make makepatch fails

Hello.

I often use make makepatch because it is very useful, but under certain conditions, new patches are not written out to PATCHDIR directory.
The condition may be patched such as /usr/ports/www/firefox/files/patch-libwebrtc-generated.
This patch includes patches for the following files

--- third_party/libwebrtc/third_party/pipewire/pipewire_gn/moz.build
+++ /dev/null

This leaves only files with the name *.orig.
The patch is generated because there is a file with the name *.orig. However, its contents are empty.
If an empty file exists, install_regenerated_patches in Mk/Scripts/smart_makepatch.sh will not do its job of writing to PATCHDIR.

All the finished patches are in ${WRKDIR}/.makepatch-tmp/staged directory, so the necessary patches should be taken from there.
This makes it look as if the patch failed to generate, is this already a known behavior?

Regards.