Static Generation Build Logs cluttered with Fetch API ERROR for Content Links that are optional.

[jsimondshiebing]

Originally opened here: agility/agility-next#25

Currently when making a request to getContentList within getCustomInitialProps any response that doesn't return with data results in a 404 message being sent to the console. When a content type has an optional reference field (an example being a blog post that has an optional related blog posts section) and a content editor chooses not to select items within the content list it still logs the 404 error message. Adding a try catch statement around the getContentList call isn't able to suppress these as no exception is actually thrown for a try catch to intercept. This results in build logs during static generation to get extremely cluttered when there are hundreds of content items that do not opt in to an optional reference field making actual build log debugging more difficult.