As you saw in the previous recipe, you need to deal with JSON data that may be incompatible with your own data. But there is another source of errors that comes from within your code.
When dealing with JSON, it often happens that the key names are repeated several times in your code. Since we are not perfect, we might create an error by typing in something that's incorrect. It's rather difficult to handle these kinds of errors as they only occur at runtime.
A common way to prevent these kinds of typos is to use constants instead of typing the key names each time you need to reference them.
