Why do I received a "invalid byte sequence " when calling a function through pg_background (encoding WIN1252)?

I am encountering a character encoding issue when using the pg_background extension for PostgreSQL. The issue occurs in a Windows/PostgreSQL 15 environment, with the raise notice statement.

To explain the problem, a minimal example using psql will be more illustrative than a detailed explanation.

The encodings are as follows:

select current_setting('client_encoding'), current_setting('server_encoding');
 current_setting | current_setting
-----------------+-----------------
 WIN1252         | UTF8
(1 row)

Create the following two functions:

create or replace function test_encoding_1() returns text language plpgsql as $$ begin raise notice 'Noël'; return 'Noël'; end $$;
create or replace function test_encoding_2() returns text language plpgsql as $$ begin return 'Noël'; end $$;

A direct call to the first function does not cause any issues (nor does the second function, for that matter):

select test_encoding_1();
NOTICE:  Noël
 test_encoding_1
-----------------
 Noël
(1 row)

A call through pg_background fails with the first function, whereas with the second function everything works fine.

select r from pg_background_result(pg_background_launch('select test_encoding_1()')) as t(r text);
ERROR:  invalid byte sequence for encoding "UTF8": 0xeb 0x6c

select r from pg_background_result(pg_background_launch('select test_encoding_2()')) as t(r text);
  r
------
 Noël
(1 row)

If we change the client encoding, the crash no longer occurs, but the characters obtained are not in the correct set:

set client_encoding to 'SQL_ASCII';

select r from pg_background_result(pg_background_launch('select test_encoding_1()')) as t(r text);
NOTICE:  Noël
   r
-------
 Noël
(1 row)

select r from pg_background_result(pg_background_launch('select test_encoding_2()')) as t(r text);
   r
-------
 Noël
(1 row)

So my question is: Is there a way to obtain a result in the correct character set (WIN1252)? Either by configuring the server or by changing the function code? Or any other solution?

This issue is resolved with pg_background 1.3.