[MASSMAIL][Code: 0, SQL State: 0A000] when "typing" from pg_catalog

Hi

I have the following function code. When trying to install, it gives me

[Code: 0, SQL State: 0A000]  FEHLER: Verweise auf andere Datenbanken 
sind nicht implementiert: pg_catalog.pg_roles.rolname
   Position: 298  [Script position: 334 - 361]

To the best of my knowledge, pg_catalog is a schema not a database, 
like information_schema. Am I missing something? And why is it not 
allowed to type from the catalogue?

I presume, this example is rather academic due to the name type.

Kind regards

Thiemo


create or replace function GRANT_SELECTS()
returns void
language plpgsql
as
$body$
     declare
         C_SCHEMA_NAME       constant 
INFORMATION_SCHEMA.SCHEMATA.SCHEMA_NAME%type :=
           'snowrunner';
--        C_ROLE_NAME         constant    name :=
         C_ROLE_NAME         constant    PG_CATALOG.PG_ROLES.ROLNAME :=
           'snowrunner_reader';
         V_SQL_STATEMENT                 text;
     begin
         -- Check the existance of the schema
         perform 1
             from INFORMATION_SCHEMA.SCHEMATA
             where SCHEMA_NAME = C_SCHEMA_NAME;
         if not found then
             raise exception 'Schema "%s" does not exist!', C_SCHEMA_NAME;
         end if;

         -- Check the existance of the role
         perform 1
             from PG_CATALOG.PG_ROLES
             where ROLNAME = C_ROLE_NAME;
         if not found then
             raise exception 'Role "%s" does not exist!', C_ROLE_NAME;
         end if;

         -- Issue grants
         V_SQL_STATEMENT := format('grant select on all tables in schema 
%i to %i', C_SCHEMA_NAME, C_ROLE_NAME);
         raise info '%', V_SQL_STATEMENT;
         execute V_SQL_STATEMENT;
         V_SQL_STATEMENT := format('grant select on all views in schema 
%i to %i', C_SCHEMA_NAME, C_ROLE_NAME);
         raise info '%', V_SQL_STATEMENT;
         execute V_SQL_STATEMENT;
         V_SQL_STATEMENT := format('grant select on all materialized 
views in schema %i to %i', C_SCHEMA_NAME, C_ROLE_NAME);
         raise info '%', V_SQL_STATEMENT;
         execute V_SQL_STATEMENT;
         commit;

         return;
     end;
$body$;