Prevent crash when importing over existing project

If the hierarchy navigator is open and expanded, we have references to
the existing sheets.  These need to be cleared when importing a new
sheet over top

Fixes https://gitlab.com/kicad/code/kicad/-/issues/20004

eeschema/files-io.cpp

@@ -578,7 +578,7 @@ bool SCH_EDIT_FRAME::OpenProjectFiles( const std::vector<wxString>& aFileSet, in
 
     TestDanglingEnds();
 
-    UpdateHierarchyNavigator( false );
+    UpdateHierarchyNavigator( false, true );
 
     wxCommandEvent changedEvt( EDA_EVT_SCHEMATIC_CHANGED );
     ProcessEventLocally( changedEvt );
@@ -1424,7 +1424,7 @@ bool SCH_EDIT_FRAME::importFile( const wxString& aFileName, int aFileType,
         SetSheetNumberAndCount();
         SyncView();
 
-        UpdateHierarchyNavigator();
+        UpdateHierarchyNavigator( false, true );
 
         wxCommandEvent e( EDA_EVT_SCHEMATIC_CHANGED );
         ProcessEventLocally( e );

eeschema/sch_edit_frame.cpp

@@ -1229,10 +1229,10 @@ void SCH_EDIT_FRAME::OnUpdatePCB()
 }
 
 
-void SCH_EDIT_FRAME::UpdateHierarchyNavigator( bool aRefreshNetNavigator )
+void SCH_EDIT_FRAME::UpdateHierarchyNavigator( bool aRefreshNetNavigator, bool aClear )
 {
     m_toolManager->GetTool<SCH_NAVIGATE_TOOL>()->CleanHistory();
-    m_hierarchy->UpdateHierarchyTree();
+    m_hierarchy->UpdateHierarchyTree( aClear );
 
     if( aRefreshNetNavigator )
         RefreshNetNavigator();

eeschema/sch_edit_frame.h

@@ -244,7 +244,7 @@ public:
     /**
      * Update the hierarchy navigation tree and history
      */
-    void UpdateHierarchyNavigator( bool aRefreshNetNavigator = true );
+    void UpdateHierarchyNavigator( bool aRefreshNetNavigator = true, bool aClear = false );
 
     /**
      * Update the hierarchy navigation tree labels.

eeschema/widgets/hierarchy_pane.cpp

@@ -209,7 +209,7 @@ void HIERARCHY_PANE::UpdateHierarchySelection()
 }
 
 
-void HIERARCHY_PANE::UpdateHierarchyTree()
+void HIERARCHY_PANE::UpdateHierarchyTree( bool aClear )
 {
     Freeze();
 
@@ -248,7 +248,9 @@ void HIERARCHY_PANE::UpdateHierarchyTree()
                 }
             };
 
-    if( !m_tree->IsEmpty() )
+    // If we are clearing the tree, don't try to get expanded nodes as they
+    // might be deleted
+    if( !aClear && !m_tree->IsEmpty() )
         getExpandedNodes( m_tree->GetRootItem() );
 
     m_list.clear();

eeschema/widgets/hierarchy_pane.h

@@ -84,7 +84,7 @@ public:
     /**
      * Update the hierarchical tree of the schematic.
      */
-    void UpdateHierarchyTree();
+    void UpdateHierarchyTree( bool aClear = false );
 
     /**
      * Updates the tree's selection to match current page