Inserting an instrument above a staff with an ambitus causes crash

1. Existing score, or new score
2. Staff with ambitus
3. Insert instrument, move above the staff with the ambitus

---> Crash

Stack trace:
1 Ms::ScoreElement::isChord scoreElement.h 263 0xfd43c0
2 Ms::Ambitus::updateRange ambitus.cpp 603 0xb316f5
3 Ms::Ambitus::setTrack ambitus.cpp 103 0xb2ed71
4 Ms::Segment::fixStaffIdx segment.cpp 800 0xa07e60
5 Ms::Segment::insertStaff segment.cpp 441 0xa06702
6 Ms::Measure::insertStaves measure.cpp 1080 0x9a38e0
7 Ms::InsertStaves::redo undo.cpp 1241 0xab3e39
8 Ms::UndoStack::push undo.cpp 307 0xaaff6d
9 Ms::Score::undo score.cpp 3663 0x9fd106
10 Ms::Measure::cmdAddStaves measure.cpp 1136 0x9a3e4d
11 Ms::Score::undoInsertStaff edit.cpp 4318 0x91bbb1
12 Ms::MuseScore::editInstrList instrdialog.cpp 309 0x63fb1a
13 Ms::MuseScore::cmd musescore.cpp 6217 0x430180
14 Ms::MuseScore::cmd musescore.cpp 6040 0x42f37f
15 Ms::MuseScore::qt_static_metacall moc_musescore.cpp 518 0x5a0ef2
16 QMetaObject::activate(QObject *, int, int, void * *) 0x68a947c8
17 QActionGroup::hovered(QAction *) 0x2ad94db2
18 QActionGroup::qt_static_metacall(QObject *, QMetaObject::Call, int, void * *) 0x2ad9573c
19 QMetaObject::activate(QObject *, int, int, void * *) 0x68a947c8
20 QAction::activate(QAction::ActionEvent) 0x2ad93e0e
...