NULL concatenation

Hi

In migration, am facing issue with NULL concatenation in plpgsql,
by concatenating NULL between any where/position to Text / Varchar, the
total string result is setting value to NULL

*In Oracle:*

declare
txt1 VARCHAR2(100) := 'ABCD';
txt2 VARCHAR2(100) := NULL;
txt3 VARCHAR2(100) := 'EFGH';
txt VARCHAR2(100) := NULL;
begin
txt:= txt1 || txt2 || txt3;
dbms_output.put_line (txt);
end;
/

abcdefgh *===>return value*

*In Postgres*

do $$
declare
txt1 text := 'ABCD';
txt2 text := NULL;
txt3 text := 'EFGH';
txt text := NULL;
begin
txt:= txt1 || txt2 || txt3;
raise notice '%', txt;
end$$ language plpgsql;

NOTICE: <NULL> *===> return value*

SQL-Server also does same like Oracle

Is there any way alternate we have for same behavior in PostgreSQL

Please

Thanks
Sridhar
OpenText