I really don't know what else to try in this reduce() challenge...

Hello, I've clearly not understood the concepts in this lesson, but I've reviewed my notes and MDN and read more in other resources and I'm just completely stuck. I have been working on this challenge for over an hour trying every possibility - even ones I absolutely knew would not work.

The error I'm receiving currently is "Something's not right. Output of hobbies: [null,null,null]". So I'm wondering if something in the map() part of the code isn't right.

I've also tried replacing the concat() method with spread syntax, but the error I get then is that "list is not iterable." That makes me think it's not the map() method that is wrong.

I've tried doing something without map, but really don't know how else to drill down into each object by just using reduce(), so I don't think that's right either. Especially since this is a lesson on nested data.

I can't even list everything I've tried because I've been working on this for so long.

Can someone provide me with some clarification on what to focus on to fix this? The built-in feedback that the result is [null, null, null] isn't helping. Other than making me guess that my map() method is wrong, but I need something more to go on. Everything I've reviewed with that map() code makes this code look correct to me.

Any guidance is much appreciated. I know I will have to work more in-depth on array iteration at this point, as this course has been extremely challenging. Thank you!

const customers = [
  {
    name: "Tyrone",
    personal: {
      age: 33,
      hobbies: ["Bicycling", "Camping"]
    }
  },
  {
    name: "Elizabeth",
    personal: {
      age: 25,
      hobbies: ["Guitar", "Reading", "Gardening"]
    }
  },
  {
    name: "Penny",
    personal: {
      age: 36,
      hobbies: ["Comics", "Chess", "Legos"]
    }
  }
];
let hobbies;

// hobbies should be: ["Bicycling", "Camping", "Guitar", "Reading", "Gardening", "Comics", "Chess", "Legos"]
// Write your code below

hobbies = customers
  .map(customer => customer.hobbies)
  .reduce((arr, list) => arr.concat(list), []);