Function warn

packages/vite/src/node/logger.ts:141–144

(msg, opts)

      output('info', msg, opts)
    },
    warn(msg, opts) {
      logger.hasWarned = true
      output('warn', msg, opts)
    },
    warnOnce(msg, opts) {
      if (warnedMessages.has(msg)) return
      logger.hasWarned = true