a Short Straight can combine with part of a Mixed Straight, but the 9 tiles of a Pure Straight (16 points) can not also be used as subsets scoring additional point(s) for Short Straight(s).

see replay record for ID:541917 Game:65521 where claiming a 7dot discard to complete 12345689dot, 333char, 44char got 16 for Pure Straight and 1 for Short Straight (plus others not relevant to this 1-point-error).