In my experience (Python and Rust) missing keys are errors, not silently converted to None: In [1]: example = {"foo": None} In [2]: print(example["foo

In my experience (Python and Rust) missing keys are errors, not silently converted to None: In [1]: example = {"foo": None} In [2]: print(example["foo"]) None In [3]: print(example["bar"]) --------------------------------------------------------------------------- KeyError Traceback (most recent call last) Cell In[3], line 1 ----> 1 print(example["bar"]) KeyError: 'bar' In [4]: print(example.get("bar", "sensible default")) sensible default If configuration values were arbitrarily nullable I would either need to deal with the possibility of nulls ending up anywhere in my program (back to The Billion Dollar Mistake) or have to have checks on parsing to say which fields are nullable or not. I acknowledge people have done silly things regarding missing keys already - but I think they should be discouraged from continuing to do so, not enabled.