Make sure that the non-existent URLs return 404. (Technically, even 500 status codes returned for several crawl attempts will make Google ignore these URLs in the future. But the apt way is to return 404.)
Assuming you are returning 404 code for these pages, Google may still report them as errors. But you need not worry about it. I think they will eventually go away.
Reference: https://support.google.com/webmasters/answer/7440203
In general, we recommend fixing only 404 error pages, not 404 excludedpages. 404 error pages are pages that you explicitly asked Google toindex, but were not found, which is obviously a bug. 404 excludedpages are pages that Google discovered through some other mechanism,such as a link from another page.