create postgresql generated column from multiple jsonb columns

How to combine multiple jsonb columns into a generated column

For single column the following statement works

alter table r 
add column txt TEXT GENERATED ALWAYS as (
         doc->'contact'->>'name'
        ) stored;

I tried the following statement without success, SQL Error [42883]: ERROR: operator does not exist: text -> unknown

alter table r 
add column txt TEXT GENERATED ALWAYS as (
         doc->'contact'->>'name' || ' ' || doc->'contact'->>'phone'
        ) stored;

Answer:

 alter table r 
    add column txt TEXT GENERATED ALWAYS as (
             (doc->'contact'->>'name') || ' ' || (doc->'contact'->>'phone')
            ) stored;