Plaid link iframe is not removed

[lorentzimys]

Hi there!
I've noticed that iframe that is created by usePlaidLink hook is not removed on successful scenario, so when I start plaid linking process multiple times - a new iframe is created each time. The only case when iframe is not recreated is when I close plaid link window and onError callback is triggered.

I've noticed that this behaviour happens because usePlaidLink effect fires an exit method on unmout, but destroy callback is not triggered:

React component to reproduce:

import React, { useEffect } from 'react';
import { PlaidLinkOptions, usePlaidLink } from 'react-plaid-link';

interface PlaidLinkProps {
  options: PlaidLinkOptions;
}

export const PlaidLink: React.FC<PlaidLinkProps> = ({ options }) => {
  const { open, ready } = usePlaidLink(options);

  useEffect(() => {
    if (ready) {
      open();
    }
  }, [ready]);

  useEffect(() => {
    return () => {
      console.log('unmount');
    };
  }, []);

  return (<></>);
};

[lorentzimys]

I think this issue is related to opened PR #226