Add config null-check as remediation

Summary:
See code comment. D42282358 (e55277c) added usage of `YGConfigIsExperimentalFeatureEnabled` during layout, in a place where we sometimes encounter a Yoga node from RN which has an unexpectedly null config.

This is a hack to stop the bleed while we add logging to figure out where the null config is coming from in RN.

Changelog: [Internal]

Reviewed By: rozele

Differential Revision: D43203521

fbshipit-source-id: 2a21143a45c712ca00d16172f734fb116d165926

ReactCommon/yoga/yoga/Yoga.cpp

@@ -4301,6 +4301,14 @@ YOGA_EXPORT void YGConfigSetExperimentalFeatureEnabled(
 YOGA_EXPORT bool YGConfigIsExperimentalFeatureEnabled(
     const YGConfigRef config,
     const YGExperimentalFeature feature) {
+  // S323291 + T145030974 + T145292944: Node config should never be null, but
+  // Yoga has a private API used by RN to set config which does not check, and
+  // we crash here where config is null. Add a null check as temporary
+  // remediation
+  if (config == nullptr) {
+    return false;
+  }
+
   return config->experimentalFeatures[feature];
 }