create function test.f_test() returns text language plpgsql as $$
begin
  raise exception 'Error test';
end
$$

create function test.f1() returns text language plpgsql as $$
declare
  l_result text;
  l_context text;
begin
  select test.f_test() into l_result;
  return l_result;
exception
  when others then
    GET STACKED DIAGNOSTICS
      l_context := pg_exception_context
    ;
    return l_context;
end
$$

create function test.f2() returns text language plpgsql as $$
declare
  l_result text;
  l_context text;
begin
  l_result := test.f_test();
  return l_result;
exception
  when others then
    GET STACKED DIAGNOSTICS
      l_context := pg_exception_context
    ;
    return l_context;
end
$$

select test.f1();
PL/pgSQL function test.f_test() line 3 at RAISE
SQL statement "select test.f_test()"
PL/pgSQL function test.f1() line 6 at SQL statement

select test.f2();
PL/pgSQL function test.f_test() line 3 at RAISE
PL/pgSQL function test.f2() line 6 at assignment