BUG #19470: PostgreSQL backend aborts (assert failure) when a prepared statement returns a composite type cast t

The following bug has been logged on the website:

Bug reference: 19470
Logged by: HaoGang Mao
Email address: haogangmao(at)gmail(dot)com
PostgreSQL version: 18.3
Operating system: Linux
Description:

Reproduction steps (minimal):
BEGIN;
CREATE TYPE foo AS (a int, b text);
PREPARE p AS SELECT CAST(ROW(1, 'hello') AS foo)::text;
EXECUTE p;
ALTER TYPE foo ALTER ATTRIBUTE a TYPE VARCHAR(100);
EXECUTE p;
COMMIT;

Expected: Error message (type modified while a prepared plan / expression is
active)
Actual: Server connection dropped; backend aborts with SIGABRT due to
assertion failure

Server log (trimmed):
TRAP: failed Assert("false"), File: "heaptuple.c", Line: 1417, PID: <pid>
... heap_deform_tuple()