possibly to automatic detection of bad variable types in plans?

I have a talk with Alex Stanev about known issue that block indexes - bad param types

postgres=# do $$
declare _id numeric = 777722;
begin
  perform * from bigtable where a = _id;
end;
$$;
DO
Time: 108,775 ms
postgres=# do $$
declare _id numeric = 777722;
begin
  perform * from bigtable where a = _id;
end;
$$;
DO
Time: 106,111 ms
postgres=# do $$
declare _id int = 777722;
begin
  perform * from bigtable where a = _id;
end;
$$;
DO
Time: 1,522 ms
postgres=# do $$
declare _id numeric = 777722;
begin
  perform * from bigtable where a = _id;
end;
$$;
DO
Time: 108,287 ms

https://github.com/okbob/plpgsql_check/issues/32