Comment by fidotron
2 days ago
From their report: "This policy data contained unintended blank fields."
This was reading fields from a database which were coming back null, not some pointer that mutates to being null after a series of nasty state transitions, and so this is very much in the junior category.
It doesn't matter where the null came from, if the language silently allows it then every skill level of engineer will make the mistake.
I don't agree that in this specific case (reading potential null data from a source) it's the kind of failure of null handling that every skill level would do, after you're experienced enough and you are reading values from somewhere with a schema you naturally check the schema to know if you ought handle nulls or not. Even if you are lazy, you want to avoid having to write null-checking and null-handling if it's unnecessary so you will go check the schema.
I haven't done such a mistake in many, many years, other kinds of null issues from internal logic I'm still very much guilty of at times, but definitely not "I forgot to handle a null from a data source I read from". It's so pervasive and common that you definitely learn from your mistakes.