crashtesting: crash seen on exit of chart

with soffice --headless --convert-to ods forum-mso-en4-569016.xlsx

and other similar

Change-Id: I908fa834c1072a9854055cad1ee6261800d76aea
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/157573
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>

chart2/source/view/main/DrawModelWrapper.cxx

@@ -101,8 +101,11 @@ DrawModelWrapper::DrawModelWrapper()
 
 DrawModelWrapper::~DrawModelWrapper()
 {
+    // normally call from ~SdrModel, but do it here explicitly before we clear m_xChartItemPool
+    implDtorClearModel();
+
     //remove m_pChartItemPool from pool chain
-    if(m_xChartItemPool)
+    if (m_xChartItemPool)
     {
         SfxItemPool* pPool = &GetItemPool();
         for (;;)

include/svx/svdmodel.hxx

@@ -252,6 +252,7 @@ public:
         tools::Long nLower = 0);
 
 protected:
+    void implDtorClearModel();
     virtual css::uno::Reference< css::uno::XInterface > createUnoModel();
 
 private:

svx/source/svdraw/svdmodel.cxx

@@ -200,7 +200,7 @@ SdrModel::SdrModel(SfxItemPool* pPool, comphelper::IEmbeddedHelper* pEmbeddedHel
     mpImpl->initTheme();
 }
 
-SdrModel::~SdrModel()
+void SdrModel::implDtorClearModel()
 {
     mbInDestruction = true;
 
@@ -216,6 +216,11 @@ SdrModel::~SdrModel()
     m_pCurrentUndoGroup.reset();
 
     ClearModel(true);
+}
+
+SdrModel::~SdrModel()
+{
+    implDtorClearModel();
 
 #ifdef DBG_UTIL
     // SdrObjectLifetimeWatchDog: