syntactically correct query gives ERROR: failed to assign all NestLoopParams to plan nodes

Hi,

running
psql -f NestLoopParams.sql
gives
psql:NestLoopParams.sql:16: ERROR: failed to assign all NestLoopParams to plan nodes
psql:NestLoopParams.sql:24: ERROR: failed to assign all NestLoopParams to plan nodes

and does not process the seemingly correct query

select u.zielnummer, gnummer.v
from u
left join b on b.btext ~ '^verr\. R(\d+)$'
left join lateral (select regexp_replace (b.btext, 'verr\. R', '')::int v)
as gnummer on true
left join lateral (select * from r where buchnummer = gnummer.v)
as r on true;

No results are given, not even row count or headers, just the error
message given above.

Everything needed to reproduce is in the file NestLoopParams.sql. The
tables do not need to be populated with data. The problem was verified
with Postgresql version 13.1 on a fresh debian sid x86_64 installation as
well as a 13.1 compiled under 32 bit i386 (Debian/Linux). Master from the
posgresql git repository (as of today's commit
f9900df5f94936067e6fa24a9df609863eb08da2) shows the same behaviour if
compiled under 32 bit i386 Debian/Linux.

I will be happy to provide more information if needed or helpful.

Thank you for your work on such an extraordinary piece of software.

Regards
Stephan