Parsing bugs are the gift that keeps giving in the age of APIs. We use a service; it works perfectly in debugging, QA, and so on. Then some user input that made its way to the web request, returns a result we just can’t parse. Unfortunately, there isn’t much we can do at this stage. We need to understand why the failure occurred and how we can workaround it and fix it.

In production, that isn’t trivial. We could log all the calls we made and all the objects passed. But this will destroy our performance and send our log storage bill through the roof. It might also put us in violation of privacy laws, since the JSON data might include private user information. This is a common problem in production since a webservice might change and trigger a serialization failure at runtime. This is especially true in polyglot environments where a Java class mapped using an API like Jackson might fail on the deserialization of a NodeJS object.