It doesn't matter that the fields are not accessible in the other case, as you are only executing one case. If you were to enclose the code in a loop that worked through the different cases then you would find that the fields that had been assigned do exist.
In your code, logically you are attempting to access something that has never been defined. Even if the field were to somehow come into existence by being assigned in the other case, the field would not have a useful value.
If you have a field whose value needs to be defined in all of the cases, you need to either assign it a value in all of the cases, or you need to assign the default value for it before the switch()
