ERROR: missing chunk number 0 for toast value

drop table if exists t;

create table t(c text);

insert into t values ('x'), (repeat(md5('abcdefghijklmnop'), 10000));

select pg_column_size(c), pg_column_size(c || '') FROM t;

CREATE OR REPLACE FUNCTION copy_toast_out() RETURNS VOID AS $$ 

declare

        v text;

BEGIN  

        SELECT c INTO v FROM t WHERE c <> 'x';

    Select 1/0;

Exception

        When Others Then

        PERFORM pg_sleep(30); -- go run "TRUNCATE t" in a 2nd session                                                                                                          

        raise notice 'length :%', length(v || ''); -- force detoast                                                                                                          

END;

$$ language plpgsql;

postgres=# select copy_toast_out();

ERROR:  missing chunk number 0 for toast value 16390 in pg_toast_16384

CONTEXT:  PL/pgSQL function copy_toast_out() line 10 at RAISE

Analysis:

Regards,