correct missing=default with GENERATED BY column

test/spec/fixtures/schema.sql

@@ -3110,3 +3110,15 @@ create table test.tbl_w_json(
   id int,
   data json
 );
+
+DO $do$
+BEGIN
+  IF current_setting('server_version_num')::INT >= 100000 THEN
+    CREATE TABLE test.channels (
+      id bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+      data jsonb DEFAULT '{"foo": "bar"}',
+      slug text
+    );
+  END IF;
+END
+$do$;