Resolves: tdf#108654 check nTabNo against maTabData size

ScViewData::DeleteTab() and DeleteTabs() never did that and worked by accident
for which commit 73dec498 removed the
grounding..

Change-Id: I95460cd017d558c073df7891551d0251009dc1d4

sc/source/ui/view/viewdata.cxx

@@ -545,6 +545,11 @@ void ScViewData::DeleteTab( SCTAB nTab )
     delete maTabData.at(nTab);
 
     maTabData.erase(maTabData.begin() + nTab);
+    if (static_cast<size_t>(nTabNo) >= maTabData.size())
+    {
+        EnsureTabDataSize(1);
+        nTabNo = maTabData.size() - 1;
+    }
     UpdateCurrentTab();
     mpMarkData->DeleteTab( nTab );
 }
@@ -558,6 +563,11 @@ void ScViewData::DeleteTabs( SCTAB nTab, SCTAB nSheets )
     }
 
     maTabData.erase(maTabData.begin() + nTab, maTabData.begin()+ nTab+nSheets);
+    if (static_cast<size_t>(nTabNo) >= maTabData.size())
+    {
+        EnsureTabDataSize(1);
+        nTabNo = maTabData.size() - 1;
+    }
     UpdateCurrentTab();
 }