Why do useFirestoreCollectionData and friends' types not reflect the fact that data can be undefined?

[devth]

👋🏻

  const catRef = useMemo(
    () =>
      collection(firestore, "categories").withConverter(converter<Category>()),
    [firestore]
  );
  const { data: categories } = useFirestoreCollectionData(catRef);
  console.log({ categories });

categories will initially be undefined, as shown by the console output:

{categories: undefined}
{categories: Array(6)}

Yet the type system shows the type of categories as:

const categories: <Category>[]

This makes it easy to run into Uncaught TypeError errors at runtime.

Alternatively, useFirestoreCollectionData could return an empty array while loading to make this safe.