code: function perform_default_fetch({ struct, op, data }) {
          if (!data && !struct.is_hydrated) {
              return undefined;
          } else if (data) {
              struct.tree = data;
              Object.defineProperties(struct, {
                  is_hydrated: { value: true },
              }); // ^ Prevent marking as unhydrated
          }
          return struct.tree;
      }
docs: -----------