been using bolt.new for a week now and its really awesome
But for 2 days in a row its unusable i got this issue for 2, and when i look at there github there are like 3 or more with same issue 3 weeks ago.
@stackblitz
got it try to create a link of index.mjs like
import { symlinkSync } from 'fs'
symlinkSync('./index.mjs', 'index')
then you can use the index without extension