Merge pull request #18742 from mike-spa/fixCrashOnDeleteAllInstrument…

…sAndUndo

Fix #18733: Crash on delete all instruments and undo

src/engraving/layout/v0/chordlayout.cpp

@@ -2292,10 +2292,11 @@ void ChordLayout::layoutChords3(const MStyle& style, const std::vector<Chord*>&
     int prevSubtype = 0;
     int prevLine = std::numeric_limits<int>::min();
 
+    bool isTab = staff->isTabStaff(tick);
     for (int i = nNotes - 1; i >= 0; --i) {
         Note* note     = notes[i];
         Accidental* ac = note->accidental();
-        if (ac && ac->subtype() == prevSubtype && note->line() == prevLine) {
+        if (ac && (isTab || (ac->subtype() == prevSubtype && note->line() == prevLine))) { // TODO: probably this function shouldn't be called at all for tab staves
             // we shouldn't have two of the same accidental on the same line.
             // if we find one that is identical to the one before it, don't lay it out
             ac->setbbox(RectF());

src/engraving/layout/v0/measurelayout.cpp

@@ -1694,21 +1694,6 @@ void MeasureLayout::removeSystemHeader(Measure* m)
         seg->setEnabled(false);
     }
     m->setHeader(false);
-
-    // remove all "generated" key signatures
-    Segment* kSeg = m->findFirstR(SegmentType::KeySig, Fraction(0, 1));
-    if (!kSeg) {
-        return;
-    }
-    for (EngravingItem* e : kSeg->elist()) {
-        if (e && e->generated()) {
-            kSeg->elist().at(e->track()) = 0;
-        }
-    }
-    kSeg->checkEmpty();
-    if (kSeg->empty()) {
-        m->remove(kSeg);
-    }
 }
 
 void MeasureLayout::addSystemTrailer(Measure* m, Measure* nm, LayoutContext& ctx)