If a follower receives an invalid request (eg non-existent index), it should return a default value.
Pro: Simplifies the protocol as there is no need to implement user-error (and thus differentiate 'bad request' from 'failed request').
Con: User code is more difficult to debug because there's no indication that you asked for something the remote device doesn't understand (apart from the data being meaningless).
If a follower receives an invalid request (eg non-existent index), it should return a default value.
Pro: Simplifies the protocol as there is no need to implement user-error (and thus differentiate 'bad request' from 'failed request').
Con: User code is more difficult to debug because there's no indication that you asked for something the remote device doesn't understand (apart from the data being meaningless).