reset previous pgssp_backend_qpid(pid) on parsing error

[legrandlegrand]

In one psql session:
SELECT
pgsa.pid,
pgsa.state,
pgsa.query,
pgssp.queryid,
pgssp.planid,
pgssp_normalize_query(pgssp.query)
FROM
pg_stat_activity pgsa
LEFT OUTER JOIN pg_stat_sql_plans pgssp
ON pgssp_backend_qpid( pgsa.pid ) = pgssp.qpid
AND pgsa.datid = pgssp.dbid
AND pgsa.usesysid = pgssp.userid
WHERE pgsa.backend_type='client backend'
and pgsa.pid != pg_backend_pid();
\watch 1

In the second psql session:
select 1;
--> should appear in session one
select a;
ERROR: column "a" does not exist
LINE 1: select a;
--> select a;
appears as query from pg_stat_activity,
but pgssp_backend_qpid(pid) is not updated (see ProcEntryArray[i])