Notion: check for slug errors before fetching page content

[madebyisaacr]

The Notion plugin fetches the full database of items, then if the content field is enabled, fetches the content for each page. This can take a long time if you have hundreds or thousands of items.

If there's a duplicate slug or missing slug value, the entire sync is cancelled and must be restarted after fixing the issues. However it doesn't check for slug issues until after fetching page content even though the data is already available before that step. The Notion plugin should be updated to check for slug errors (duplicate or missing slugs) between fetching the database items and fetching page content to save time.