[trunk] Crash when opening score that contains tied 1/8 note created in 1.1

Open the enclosed score which was produced in 1.1.

Works OK with the same score created with trunk version (2nd attachment).

Crashes in the code inserted for R5272, Beam:add (sorting):
if (_elements[i]->segment()->tick() >= a->segment()->tick()) {
Segment::tick
return _tick + measure()->tick();

this is null.