Apply Wayne's suggestion for better error recov

No need to exit the draw routine on a bad layer, we can skip that layer
and continue processing the valid elements

common/view/view_group.cpp

@@ -122,7 +122,7 @@ void VIEW_GROUP::ViewDraw( int aLayer, VIEW* aView ) const
 
         for( int i = 0; i < item_layers_count; i++ )
         {
-            wxCHECK_RET( item_layers[i] <= LAYER_ID_COUNT, wxT( "Invalid item layer" ) );
+            wxCHECK2_MSG( item_layers[i] <= LAYER_ID_COUNT, continue, wxT( "Invalid item layer" ) );
 
             if( layer_item_map.count( item_layers[i] ) == 0 )
             {