PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> Reproduced starting from d55322b0d.
BTW, d55322b0d simply made it easy to trigger the bug from psql.
If I use current psql to connect to older servers, I can demonstrate
crashes (or sometimes "stack depth limit exceeded") back to v12.
Pre-v12 is immune because it just returns a command tag of EXECUTE
regardless of what is in the prepared statement.
That being the case, maybe we should band-aid this by returning
EXECUTE if the prepared statement is empty.
regards, tom lane