How do I access object return from mongo database in React?

I'm making a GET request from a my App react component, but I'm having trouble rendering the returned data.

I'm making an GET request with axios, and then setting the returned data to a state variable called reviews :

useEffect(() => {
    axios.get('http://localhost:3000/all-reviews')
  .then((allReviews) => {
   setReviews(allReviews)
  })
  },[])

I checked React dev tools in the browser, and found that the data (an array of four objects) had indeed been set to state:

State:
{config: {…}, data: Array(4), headers: {…}, request…}

data:
[{…}, {…}, {…}, {…}]
status:
200
statusText:
"OK"

headers:
{access-control-allow-origin: "*", content-length: …}

config:
{adapter: ƒ xhrAdapter() {}, data: undefined, heade…}
request:
{DONE: 4, HEADERS_RECEIVED: 2, LOADING: 3, OPENED: …}
new entry: 
""
Effect:
ƒ () {}

To access the data, I logged reviews.data to the console, which yielded [object Object],[object Object],[object Object],[object Object]

However when I tried to map through this data, I got the following error:

Uncaught TypeError: Cannot read property 'map' of undefined

So, how do I access the properties within the returned object?

Here's the react component in full:

import React, {useState, useEffect} from 'react'
import axios from 'axios'

const App = () => {
  const [reviews, setReviews] = useState([])

  useEffect(() => {
    axios.get('http://localhost:3000/all-reviews')
  .then((allReviews) => {
   setReviews(allReviews)
  })
  },[])

  // console.log(`this is reviews state: ${reviews && reviews.data && reviews.data[0].title}`)

  console.log(`this is reviews state: ${reviews.data}`)
  return (
    <>
    <h1>React development has begun!</h1>
    {
      reviews.data.map(item => {
        <h2>{item.title}</h2>
      })
    }
    </>
  )
}

export default App

And here's the Schema/Model for the documents being returned:

const mongoose = require('mongoose')
const Schema = mongoose.Schema

const reviewSchema = new Schema({
    userName:String,
    stars:Number,
    title:String,
    photo:String,
    blurb:String
}, {timestamps:true})

const Review = mongoose.model('review', reviewSchema)

module.exports = Review