Filter includes false is not a function

Question

I am searching an array within my object to return an object with only the matched values in my categories array using filter & includes. For some reason whenever I try to run my function keep getting

TypeError: Cannot read property 'includes' of null

or

TypeError: false is not a function

if I use the find function within my filter.

What am I doing wrong?

[{
    "entryTitle": "What Is Sports Medicine Acupuncture?",
    "date": "September 30 2015",
    "categories": ["Knee Pain"],
    "type": false
}, {
    "entryTitle": "Providing Quality Care During The COVID-19 Pandemic",
    "date": "March 23 2020",
    "categories": null,
    "type": false
}, {
    "entryTitle": "Correcting Severe Antalgic Posture & Gait",
    "date": "May 09 2020",
    "categories": ["Back Pain"],
    "type": true
}, {
    "entryTitle": "The Successful Treatment Of Sciatica And Low Back Pain With Sports Medicine Acupuncture®",
    "date": "July 24 2020",
    "categories": ["Back Pain"],
    "type": true
}, {
    "entryTitle": "Treating A Quad Strain For A Super Heavyweight Powerlifter Before The KERN US Open Powerlifting Meet",
    "date": "June 28 2018",
    "categories": ["Knee Pain"],
    "type": true
}, {
    "entryTitle": "Treating A High Hamstring Strain Before A Powerlifting Competition Using Sports Medicine Acupuncture®",
    "date": "June 05 2020",
    "categories": ["Back Pain"],
    "type": true
}, {
    "entryTitle": "Free Acupuncture Treatments For Veterans Through The Veterans Choice Program",
    "date": "June 08 2017",
    "categories": ["Back Pain", "Disc Herniation", "Shoulder Pain"],
    "type": true
}, {
    "entryTitle": "The Treatment Of Whiplash Related Injuries With Acupuncture",
    "date": "March 04 2016",
    "categories": ["Disc Herniation"],
    "type": false
}]

My function

const [selected, setSelected] = useState("all")
const [posts, setPosts] = useState(postData)

const filterPosts = value => {
  let posts = postData
  if (value !== "all") {
    posts = postData.filter(post => post.categories.includes(value))
    //posts = postData.filter(post => post.categories.find(post.categories === value))

  }
  setSelected(value)
  setPosts(posts)
}

Expected results

{
    "entryTitle": "What Is Sports Medicine Acupuncture?",
    "date": "September 30 2015",
    "categories": ["Knee Pain"],
    "type": false
},
 {
    "entryTitle": "Treating A Quad Strain For A Super Heavyweight Powerlifter Before The KERN US Open Powerlifting Meet",
    "date": "June 28 2018",
    "categories": ["Knee Pain"],
    "type": true
},

Answer 1

This entry

{
    "entryTitle": "Providing Quality Care During The COVID-19 Pandemic",
    "date": "March 23 2020",
    "categories": null,
    "type": false
}

has categories set to null. You can't do includes on it.

Fix it using optional chaining, or check the existence before:

post.categories?.includes(value)

or

post.categories && post.categories.includes(value)