timestamp out of range while casting return value to function'sreturn type

Hi all

I created a function that ought to return a timestamptz (another  
likewise timestamp) but calling it, I get mentionied error. What do I  
miss? I tried to return a timestamp of the year 2000 to no avail.

Call: select utils.get_max_timestamptz();
--

Function
--
create or replace function GET_MAX_TIMESTAMPTZ()
   returns timestamptz
   language plpgsql
   immutable
   -- Include the hosting schema into search_path so that dblink
   -- can find the pglogger objects. There is no need to access
   -- objects in other schematas not covered with public.
   as
$body$
     begin
         -- highest timestamps on 64bit lubuntu vanilla PostgreSQL 11.3
         return '294277-01-01 00:59:59.999999'::timestamptz;
     end;
$body$;

Kind regards

Thiemo

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