run_oci: remove use of base::JSONReader::ValueWithError error_code

The field would be deleted after libchrome r822064 urpev.
Check validity of by checking value field is not base::nullopt.

BUG=chromium:1144735
TEST=cros_run_unit_tests --board=eve --packages run_oci

Disallow-Recycled-Builds: hatch-cq, hatch-arc-r-cq, drallion-cq
Change-Id: I54829eefab27ca6843dd0f71a7187b114028faec
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2595756
Commit-Queue: Qijiang Fan <fqj@google.com>
Tested-by: Qijiang Fan <fqj@google.com>
Reviewed-by: Qijiang Fan <fqj@google.com>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
diff --git a/run_oci/container_config_parser.cc b/run_oci/container_config_parser.cc
index 9def89f..d9c26bc 100644
--- a/run_oci/container_config_parser.cc
+++ b/run_oci/container_config_parser.cc
@@ -950,7 +950,7 @@
                           OciConfigPtr const& config_out) {
   auto result = base::JSONReader::ReadAndReturnValueWithError(
       config_json_data, base::JSON_PARSE_RFC);
-  if (result.error_code != base::JSONReader::JSON_NO_ERROR) {
+  if (!result.value) {
     LOG(ERROR) << "Fail to parse config.json: " << result.error_message;
     return false;
   }