Fix #4070 don't increment aggregate length on invalid members

src/ifcparse/IfcParse.cpp

@@ -782,6 +782,8 @@ size_t IfcParse::IfcFile::load(unsigned entity_instance_name, const IfcParse::en
                     filler.push_back(entity);
                 } catch (IfcException& e) {
                     Logger::Message(Logger::LOG_ERROR, e.what());
+                    // #4070 We didn't actually capture an aggregate entry, undo length increment.
+                    return_value--;
                 }
             } else {
                 filler.push_back(new TokenArgument(next));