Pipe transforms errors through transformation pipelines

Summary:
public

Fixes an issue on the transforms pipeline which caused not to pipe errors that occured on the external transformer to JSTransformer.

Reviewed By: yungsters

Differential Revision: D2806498

fb-gh-sync-id: c9347d1957a3a9320b3f177ff9b19bf3802087a0

packager/react-packager/src/JSTransformer/worker.js

@@ -32,6 +32,11 @@ function internalTransforms(sourceCode, filename, options) {
 }
 
 function onExternalTransformDone(data, callback, error, externalOutput) {
+  if (error) {
+    callback(error);
+    return;
+  }
+
   var result;
   if (data.options.enableInternalTransforms) {
     result = internalTransforms(