The issue here was sometimes an output socket of a `Group Input` node has a
reference to a data-block. The value stored on these output sockets are never
used, and thus is not exposed in the UI which made it impossible for the user to
find that there still is a data-block reference.
The root cause for this seems to have been fixed a few releases ago. I can
reproduce that the pointer was set in 3.3, but not in 3.6.
This patch only adds some versioning to remove the unnecessary data-block
references to fix old files that might have this issue (e.g. the file from the
report).
Pull Request: https://projects.blender.org/blender/blender/pulls/131900
6924be003e