Strange!!! why vite bundle unused content into?

[wenjoy]

Repo to reproduce the issue: https://github.com/wenjoy/vite-bundle-issue
It's good to bundle with this file.

import sqlite3 from 'sqlite3'

export function add() {
  return `888` 
}

but with below, vite will bundle sqlite3 into, see snapshot:

import sqlite3 from 'sqlite3'

export function add() {
  return `888` 
}


function init() {
   let db: sqlite3.Database;
   db = new sqlite3.Database('')
}