Don't assert (or crash) on shutdown.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/20433

common/eda_draw_frame.cpp

@@ -1228,7 +1228,7 @@ void EDA_DRAW_FRAME::ShowChangedLanguage()
 
 void EDA_DRAW_FRAME::UpdateProperties()
 {
-    if( !m_propertiesPanel || !m_propertiesPanel->IsShownOnScreen() )
+    if( m_isClosing || !m_propertiesPanel || !m_propertiesPanel->IsShownOnScreen() )
         return;
 
     m_propertiesPanel->UpdateData();

eeschema/sch_edit_frame.cpp

@@ -1176,7 +1176,8 @@ void SCH_EDIT_FRAME::OnModify()
     if( GetScreen() )
         GetScreen()->SetContentModified();
 
-    m_autoSaveRequired = true;
+    if( m_isClosing )
+        return;
 
     if( GetCanvas() )
         GetCanvas()->Refresh();

eeschema/symbol_editor/symbol_edit_frame.cpp

@@ -1030,11 +1030,13 @@ void SYMBOL_EDIT_FRAME::OnModify()
     EDA_BASE_FRAME::OnModify();
 
     GetScreen()->SetContentModified();
-    m_autoSaveRequired = true;
 
     if( !IsSymbolFromSchematic() )
         storeCurrentSymbol();
 
+    if( m_isClosing )
+        return;
+
     GetLibTree()->RefreshLibTree();
 
     if( !GetTitle().StartsWith( "*" ) )

pagelayout_editor/pl_editor_frame.cpp

@@ -377,6 +377,9 @@ void PL_EDITOR_FRAME::OnModify()
 
     GetScreen()->SetContentModified();
 
+    if( m_isClosing )
+        return;
+
     UpdateTitleAndInfo();
 }
 

pcbnew/footprint_edit_frame.cpp

@@ -979,6 +979,10 @@ void FOOTPRINT_EDIT_FRAME::ShowChangedLanguage()
 void FOOTPRINT_EDIT_FRAME::OnModify()
 {
     PCB_BASE_FRAME::OnModify();
+
+    if( m_isClosing )
+        return;
+
     Update3DView( true, true );
     GetLibTree()->RefreshLibTree();
 

pcbnew/pcb_base_frame.cpp

@@ -996,10 +996,11 @@ void PCB_BASE_FRAME::OnModify()
     EDA_BASE_FRAME::OnModify();
 
     GetScreen()->SetContentModified();
-    m_autoSaveRequired = true;
-
     GetBoard()->IncrementTimeStamp();
 
+    if( m_isClosing )
+        return;
+
     UpdateStatusBar();
     UpdateMsgPanel();
 }

pcbnew/pcb_edit_frame.cpp

@@ -1829,13 +1829,16 @@ void PCB_EDIT_FRAME::SetLastPath( LAST_PATH_TYPE aType, const wxString& aLastPat
 void PCB_EDIT_FRAME::OnModify()
 {
     PCB_BASE_FRAME::OnModify();
+    m_ZoneFillsDirty = true;
+
+    if( m_isClosing )
+        return;
 
     Update3DView( true, GetPcbNewSettings()->m_Display.m_Live3DRefresh );
 
     if( !GetTitle().StartsWith( wxT( "*" ) ) )
         UpdateTitle();
 
-    m_ZoneFillsDirty = true;
 }