?? is displayed when value is still recent #109
Description
If a fetch for a new glucose value fails (network conditions, glitch, ...) the icon will show '??'
However, if there's still a recent value available, then it should be shown rather than '??'.
How recent, that remains to be seen. The icon will show '~' if no value was received for 30minutes.
If there's a network glitch & value is > 30m => '??'
If there's a network glitch & value is < 30m => TBD