[vpr][base] set type name to nullptr if type is null

Author: amin1377

vpr/src/base/setup_vib_grid.cpp

@@ -302,8 +302,9 @@ static void set_vib_grid_block_type(int priority,
 
     if (priority < max_priority_type_loc.priority) {
         //Lower priority, do not override
+        std::string type_name = (type == nullptr) ? "nullptr" : type->get_name();
         std::string msg = vtr::string_fmt("Not creating block '%s' at (%zu,%zu) since overlaps block '%s' at (%zu,%zu) with higher priority (%d > %d)\n",
-                                          type->get_name().c_str(), x_root, y_root, max_priority_type_loc.type->get_name().c_str(), max_priority_type_loc.x, max_priority_type_loc.y,
+                                          type_name.c_str(), x_root, y_root, max_priority_type_loc.type->get_name().c_str(), max_priority_type_loc.x, max_priority_type_loc.y,
                                           max_priority_type_loc.priority, priority);
         VTR_LOG_DEBUG(msg.c_str());
         return;