API call in Typescript functional component

[MysteryAchievement]

I am trying to write a timer functional component in Typescript that can be started with a button. Here is some heavily stripped down example code:

const TimerComponent = () => {
  const countdownRef = useRef();

  const startTimer = () => {
    countdownRef.current.api.start();
  };

  const notify = () => toast('Expired!');

  return (
    <>
      <Countdown date={date} controlled={true} onComplete={notify} autoStart={false}>
      <ToastContainer />
      </Countdown>
      <StartButton onClick={startTimer}>Start</StartButton>
    </>
  );
};
export default TimerComponent;

The problem is eslint complains that

countdownRef.current.api.start();

Object is possibly 'undefined'.
Unsafe call of an any typed value.

Where can I find type information for the package and how do I get around this possibly undefined Object issue?

[MysteryAchievement]

I tried this as well:

const countdownRef = useRef();
  const api = countdownRef.current.api as CountdownApi;

  const startTimer = () => {
    api.start();
  };

I still get Object is possibly 'undefined' for:

countdownRef.current

and Unsafe call of an any typed value for

api.start();

[ndresx]

Hi, you should be able to type and use it this way:

const countdownRef = useRef<Countdown>();

const startTimer = () => {
  countdownRef.current?.getApi().start();
};