Reserved words used as aliases cause a crash

Input data

SELECT set.foo FROM settings AS set

Here's a more complex example (the error is a bit different):

SELECT id AS srvid,
  CASE WHEN id = $1 THEN $2
  ELSE
     COALESCE(alias, hostname || $3 || port)
  END AS alias,
  CASE WHEN id = $4 THEN $5 ELSE hostname END as hostname,
  CASE WHEN id = $6 THEN $7 ELSE port END AS port,
  CASE WHEN id = $8 THEN set.setting
      ELSE s.version::text
  END AS version
FROM public.powa_servers s
LEFT JOIN pg_settings set ON set.name = $9 AND s.id = $10

Usage

• How are you calling / using the library?

import { formatDialect, postgresql } from "sql-formatter";
formatDialect(value, { dialect: postgresql })

Tested in the online demo as well.

• What SQL language(s) does this apply to?
  PostgreSQL, but the first example fails with any dialect with the same error

• Which SQL Formatter version are you using?
  15.4.6

Start by reproducing the two SQL examples through formatDialect with the PostgreSQL dialect, then compare the first query across dialects. Trace how reserved words are handled when used as aliases and add regression coverage showing that both queries format without crashing while preserving their aliases.