Possible problem on PROPOSAL branch/MR

For demonstration I committed a minimal change to add_proposal_process_rebase !245 (merged) :

https://gitlab.ikp.kit.edu/AirShowerPhysics/corsika/-/merge_requests/245/diffs?commit_id=0c4fc964c8728b2ca082fb99ee588be9807c7a0a

which can easily be reverted later, if we wish (but we want to have this in principle).

Based on the PROPOSAL example I edited the vertical_EAS to include PROPOSAL, but during init it fails with an exception:

"ROPOSAL could not find corresponding builder"

Why?