why false when user mathjax in node

Created by: TangsWang

import mathjax from 'mathjax'
.....
      mathjax.init({
        loader: {
          load: ['input/tex'],
        }
      })
        .then(mj => {
          if (!mj) {
            reject(`mathjax instance is undefined.`)
          } else {
            mj.tex2mmlPromise(math).then(mml => resolve(mml))
          }
        })
        .catch(err => reject(err.message))

will report error: mathjax instance is undefined.

i was using nuxt3. it is ok on local, but error on vercel. i don't know why?