Comment by piva00

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.