What is “not assignable to parameter of type never” error in typescript?

Question

Code is:

const foo = (foo: string) => {
  const result = []
  result.push(foo)
}

I get the following TS error:

[t

Answer 1

I got the same error in ReactJS function component, using ReactJS useState hook. The solution was to declare the type of useState at initialisation:

const [items , setItems] = useState([]); // replace IItem[] with your own typing: string, boolean...