lib: Fixed json-parser to correctly parse numbers at EOF.

lib: Fixed json-parser to correctly parse numbers at EOF.

Numbers are a bit special compared to others, because they don't have any
clear character indicating that the number ends. So we can only assume that
the number is finished when EOF is reached, although even that isn't
necessarily correct in case the stream is terminated unexpectedly.

This change is in prepartion for the next change. With current JSON parser
this issue could never happen because "}" was expected just before EOF.