fixed error when requesting last continuation

[Kylof61034]

This error appears, when requesting the last continuation. With this little fix it now works fine.

node_modules\yt-channel-info\app\youtube-grabber.js:160
      nextContinuation = continuationItem[0].continuationItemRenderer.continuationEndpoint.continuationCommand.token
                                             ^

TypeError: Cannot read property 'continuationItemRenderer' of undefined
    at Function.getChannelVideosMore (node_modules\yt-channel-info\app\youtube-grabber.js:160:46)
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (node:internal/process/task_queues:94:5)

The problem was that continuationItem was not undefined, but an empty array.

[PrestonN]

LGTM. Thank you!