I encountered the same error when testing with hugo server locally (also ~2 weeks ago, never appeared before) but got rid of it using ignoreErrors = ["error-remote-getjson"]
See below:
Local machine:
Microsoft Windows [Version 10.0.18362.1139]
Hugo version:
Hugo Static Site Generator v0.77.0-EF290125 windows/amd64 BuildDate: 2020-10-30T10:13:29Z
Is there maybe an issue with the Gitlab Hugo version not being on .77 yet and not processing the ignoreError flag in the config.toml?
Fixed it thanks to https://github.com/Mitrichius/hugo-theme-anubis/issues/70#issuecomment-722902911 who pointed out that the Instagram shortcode was removed from the rich-content.md example in the Hugo exampleSite (see here). I had the file still in my content/posts directory and that broke the build. Removing the shortcode there as well fixed the build.