feat: mapper function for wishlist dto;

refactor: made database fields for wishlist object not null

sqlc/schema.sql

@@ -101,9 +101,9 @@ CREATE TABLE IF NOT EXISTS "wish_lists" (
   profile_id BIGINT UNIQUE NOT NULL REFERENCES profiles(id) ON DELETE CASCADE,
   hidden BOOLEAN NOT NULL DEFAULT FALSE,
   name VARCHAR(32) NOT NULL DEFAULT 'Wishes',
-  icon_name VARCHAR(64),
-  color VARCHAR(7),
-  color_grad VARCHAR(7),
+  icon_name VARCHAR(64) NOT NULL DEFAULT '',
+  color VARCHAR(7) NOT NULL DEFAULT '',
+  color_grad VARCHAR(7) NOT NULL DEFAULT '',
   deleted BOOLEAN NOT NULL DEFAULT FALSE
 );