Let's just say "this HTTP endpoint expects its body to be JSON" and "we use a library that allows invalid JSON" (e.g. trailing commas) aren't exactly a good com

Let's just say "this HTTP endpoint expects its body to be JSON" and "we use a library that allows invalid JSON" (e.g. trailing commas) aren't exactly a good combination. Code easily ends up depending on the specific library's quirks and config, regardless of what the actual contract said.