I'm learning backend node/express. In this block of code I'm trying to send some data to backend but i get Uncaught (in promise) TypeError: Failed to fetch. Thank you.

Backend:

    const path = require("path")
const express =require("express")
const cors = require('cors')
const app = express()

const publicPath = path.join(__dirname, "..","client", 'dist')
const publicPath2 = path.join(__dirname, "..","client", 'public')
const port = process.env.PORT || 3000


app.use(express.urlencoded({extended: true}))
app.use(express.json())
app.use(cors())
app.use(express.static(publicPath))
app.use(express.static(publicPath2))

app.use(express.urlencoded)


app.get("*", (req,res) => {
    res.sendFile(path.join(publicPath, 'index.html'))
})

//edit

app.post('/api', (req, res) => {
console.log('I got a req')
console.log(req.body)
const data = req.body
res.json({
    status:'success',
    cart:data.cart
})

})

app.listen(port, () => {
    console.log('server is up')
})

frontEnd

const submitAuthor = async () => {
        const result = await fetch('/api', {
          method: 'POST',
          headers: {
            'Content-Type': 'application/json'
          },
          body: JSON.stringify(cart)
        })
        const data= await result.json()
        console.log(data)
      }

Edited the response part.