Crash involving hairpins when deleting a staff

Original score: Excellence.mscz

Always a crash by deleting the 2th staff, with the reduced file: 1minimal trumpet.mscz

By deleting the hairpin last measure (original measure 14), the crash is fixed: 1'minimal trumpet.mscz

But, if adding a new hairpin same measure, no more crash. Something went wrong before (score created there is three years?) Right now, I can't reproduce from scratch.

The pull request on this issue: https://github.com/musescore/MuseScore/pull/4018
The problem in reproducing this issue is that in the given scores there are empty staves which are hidden by the scores' style settings. These empty staves contained hairpins, and when trying to remove those empty staves the hairpins were not correctly removed in all exceprts, as explained in the pull request's description.

Fixed in branch master, commit 288e0c349e

fix #276578: remove spanners for each staff when removing staves

Add a test to ensure that after removing a staff all elements belonging to it are also removed

Fixed in branch master, commit 5ad448cfa5

Merge pull request #4018 from dmitrio95/remove-staff-crash

fix #276578: remove spanners for each staff when removing staves

Automatically closed -- issue fixed for 2 weeks with no activity.

Automatically closed -- issue fixed for 2 weeks with no activity.