Combine all existing measurement into one 'final measurement'.
In case a single result has been recorded, it will be used as the final result as-is.
Otherwise, all recorded results are sent to a server, which will then combine them into one and return this 'final result'.
- At least one processed measurement must exist.
- Stores the result in a result variable.
- On success: The measurement has been successfully retrieved and stored.
- On no measurement: No processed measurement exists (e.g. by deleting bad results, or by calling this function before measuring and processing the result).