The P0004 assert_failure exception assert_failure exception seems to be unhandleable

I just stumbled on the fact that the "assert_failure" exception seems to be unhandleable. My test is at the end.

Is this intended?

I looked at the section:

«
43.9.2. Checking Assertions
https://www.postgresql.org/docs/current/plpgsql-errors-and-messages.html#PLPGSQL-STATEMENTS-ASSERT
»

It says this:

«
Note that ASSERT is meant for detecting program bugs, not for reporting ordinary error conditions. Use the RAISE statement, described above, for that.
»

But it takes quite a stretch of the imagination to infer that this means that the "assert_failure" exception cannot be handled.

B.t.w. this (in the same "43.9. Errors and Messages" chapter) looks like a typo:

«
If no condition name nor SQLSTATE is specified in a RAISE EXCEPTION command, the default is to use ERRCODE_RAISE_EXCEPTION (P0001).
»

The spelling "errcode_raise_exception()" makes it look like a built-in function. I believe that this is meant:

«
If no condition name nor SQLSTATE is specified in a RAISE EXCEPTION command, the outcome is as if this:

ERRCODE = "RAISE_EXCEPTION"

or this:

ERRCODE = "P0001"

was used
»

----------------------------------------------------------------------
-- The test

create function demo_outcome(which in text)
returns text
language plpgsql
as $body$
declare
err text not null := '';
msg text not null := '';
hint text not null := '';
n int not null := 0;
begin
case which
when 'OK' then
n := 42;

when 'null_value_not_allowed' then
n := null;

when 'raise_exception' then
raise exception using
errcode = 'raise_exception',
message = 'U1234: Not allowed!',
hint = 'Do something else!';

when 'assert_failure' then
assert false, 'Assert failed';
end case;
return 'no error';
exception when others then
get stacked diagnostics
err = returned_sqlstate,
msg = message_text,
hint = pg_exception_hint;
return 'Handled: '||err||' | '||msg||' | '||hint;
end;
$body$;

\set VERBOSITY verbose
\t on
\o spool.txt
select demo_outcome('OK');
select demo_outcome('null_value_not_allowed');
select demo_outcome('raise_exception');
\o
\t off

It outputs this to "spool.txt".

no error

Handled: 22004 | null value cannot be assigned to variable "n" declared NOT NULL |

Handled: P0001 | U1234: Not allowed! | Do something else!

But doing this:

select demo_outcome('assert_failure');

causes this outcome:

ERROR: P0004: Assert failed
CONTEXT: PL/pgSQL function demo_outcome(text) line 22 at ASSERT
LOCATION: exec_stmt_assert, pl_exec.c:3918