Don't assume SCH_SYMBOLs have a LIB_SYMBOL when resolving embedded files

Fixes https://gitlab.com/kicad/code/kicad/-/issues/21497

eeschema/dialogs/dialog_sim_model.cpp

@@ -88,7 +88,8 @@ DIALOG_SIM_MODEL<T>::DIALOG_SIM_MODEL( wxWindow* aParent, EDA_BASE_FRAME* aFrame
         m_filesStack.push_back( symbol->Schematic()->GetEmbeddedFiles() );
     }
 
-    m_filesStack.push_back( aSymbol.GetEmbeddedFiles() );
+    if( EMBEDDED_FILES* symbolEmbeddedFiles = aSymbol.GetEmbeddedFiles() )
+        m_filesStack.push_back( symbolEmbeddedFiles );
 
     m_libraryModelsMgr.SetFilesStack( m_filesStack );
     m_builtinModelsMgr.SetFilesStack( m_filesStack );

eeschema/sch_edit_frame.cpp

@@ -1488,7 +1488,9 @@ void SCH_EDIT_FRAME::RefreshOperatingPointDisplay()
             {
                 std::vector<EMBEDDED_FILES*> embeddedFilesStack;
                 embeddedFilesStack.push_back( m_schematic->GetEmbeddedFiles() );
-                embeddedFilesStack.push_back( symbol->GetEmbeddedFiles() );
+
+                if( EMBEDDED_FILES* symbolEmbeddedFiles = symbol->GetEmbeddedFiles() )
+                    embeddedFilesStack.push_back( symbolEmbeddedFiles );
 
                 simLibMgr.SetFilesStack( std::move( embeddedFilesStack ) );
 

eeschema/sch_field.cpp

@@ -741,7 +741,9 @@ void SCH_FIELD::OnScintillaCharAdded( SCINTILLA_TRICKS* aScintillaTricks,
 
                     std::vector<EMBEDDED_FILES*> embeddedFilesStack;
                     embeddedFilesStack.push_back( schematic->GetEmbeddedFiles() );
-                    embeddedFilesStack.push_back( symbol->GetEmbeddedFiles() );
+
+                    if( EMBEDDED_FILES* symbolEmbeddedFiles = symbol->GetEmbeddedFiles() )
+                        embeddedFilesStack.push_back( symbolEmbeddedFiles );
 
                     mgr.SetFilesStack( std::move( embeddedFilesStack ) );
 

eeschema/sch_item.cpp

@@ -685,8 +685,12 @@ const std::vector<wxString>* SCH_ITEM::GetEmbeddedFonts()
 {
     if( SCHEMATIC* schematic = Schematic() )
         return schematic->GetEmbeddedFiles()->GetFontFiles();
-    else if( SYMBOL* symbol = GetParentSymbol() )
-        return symbol->GetEmbeddedFiles()->UpdateFontFiles();
+
+    if( SYMBOL* symbol = GetParentSymbol() )
+    {
+        if( EMBEDDED_FILES* symbolEmbeddedFiles = symbol->GetEmbeddedFiles() )
+            return symbolEmbeddedFiles->UpdateFontFiles();
+    }
 
     return nullptr;
 }

eeschema/sch_symbol.cpp

@@ -1977,6 +1977,11 @@ BITMAPS SCH_SYMBOL::GetMenuImage() const
 
 EMBEDDED_FILES* SCH_SYMBOL::GetEmbeddedFiles()
 {
+    std::unique_ptr<LIB_SYMBOL>& libSymbolRef = GetLibSymbolRef();
+
+    if( !libSymbolRef )
+        return nullptr;
+
     return GetLibSymbolRef()->GetEmbeddedFiles();
 }
 
@@ -1991,7 +1996,7 @@ void SCH_SYMBOL::MirrorHorizontally( int aCenter )
 
     for( SCH_FIELD& field : m_fields )
     {
-        // Move the fields to the new position because the symbol itself has moved.
+        // Move the fields to the new position because the sy:Qmbol itself has moved.
         VECTOR2I pos = field.GetTextPos();
         pos.x -= dx;
         field.SetTextPos( pos );

eeschema/sim/sim_model.cpp

@@ -1689,7 +1689,8 @@ void SIM_MODEL::MigrateSimModel( T& aSymbol, const PROJECT* aProject )
             embeddedFilesStack.push_back( symbol->Schematic()->GetEmbeddedFiles() );
         }
 
-        embeddedFilesStack.push_back( aSymbol.GetEmbeddedFiles() );
+        if( EMBEDDED_FILES* symbolEmbeddedFiles = aSymbol.GetEmbeddedFiles() )
+            embeddedFilesStack.push_back( symbolEmbeddedFiles );
 
         libMgr.SetFilesStack( std::move( embeddedFilesStack ) );
 

eeschema/sim/simulator_frame_ui.cpp

@@ -1666,7 +1666,9 @@ void SIMULATOR_FRAME_UI::UpdateTunerValue( const SCH_SHEET_PATH& aSheetPath, con
 
     std::vector<EMBEDDED_FILES*> embeddedFilesStack;
     embeddedFilesStack.push_back( m_schematicFrame->Schematic().GetEmbeddedFiles() );
-    embeddedFilesStack.push_back( symbol->GetEmbeddedFiles() );
+
+    if( EMBEDDED_FILES* symbolEmbeddedFiles = symbol->GetEmbeddedFiles() )
+        embeddedFilesStack.push_back( symbolEmbeddedFiles );
 
     mgr.SetFilesStack( std::move( embeddedFilesStack ) );
 

eeschema/tools/sch_editor_control.cpp

@@ -540,7 +540,11 @@ int SCH_EDITOR_CONTROL::SimProbe( const TOOL_EVENT& aEvent )
 
                         std::vector<EMBEDDED_FILES*> embeddedFilesStack;
                         embeddedFilesStack.push_back( m_frame->Schematic().GetEmbeddedFiles() );
-                        embeddedFilesStack.push_back( symbol->GetEmbeddedFiles() );
+
+                        EMBEDDED_FILES* symbolEmbeddedFile = symbol->GetEmbeddedFiles();
+
+                        if( symbolEmbeddedFile )
+                            embeddedFilesStack.push_back( symbolEmbeddedFile );
 
                         mgr.SetFilesStack( std::move( embeddedFilesStack ) );