Added an inline C++ function to replace a deprecated nan function

src/node/ext/call.cc

@@ -619,7 +619,7 @@ NAN_METHOD(Call::StartBatch) {
       call->wrapped_call, &ops[0], nops, new struct tag(
           callback, op_vector.release(), resources), NULL);
   if (error != GRPC_CALL_OK) {
-    return NanThrowError("startBatch failed", error);
+    return NanThrowError(nanErrorWithCode("startBatch failed", error));
   }
   CompletionQueueAsyncWorker::Next();
   NanReturnUndefined();
@@ -633,7 +633,7 @@ NAN_METHOD(Call::Cancel) {
   Call *call = ObjectWrap::Unwrap<Call>(args.This());
   grpc_call_error error = grpc_call_cancel(call->wrapped_call, NULL);
   if (error != GRPC_CALL_OK) {
-    return NanThrowError("cancel failed", error);
+    return NanThrowError(nanErrorWithCode("cancel failed", error));
   }
   NanReturnUndefined();
 }

src/node/ext/call.h

@@ -51,6 +51,19 @@ namespace node {
 using std::unique_ptr;
 using std::shared_ptr;
 
+/**
+ * Helper function for throwing errors with a grpc_call_error value.
+ * Modified from the answer by Gus Goose to
+ * http://stackoverflow.com/questions/31794200.
+ */
+inline v8::Local<v8::Value> nanErrorWithCode(const char *msg,
+                                             grpc_call_error code) {
+    NanEscapableScope();
+    v8::Local<v8::Object> err = NanError(msg).As<v8::Object>();
+    err->Set(NanNew("code"), NanNew<v8::Uint32>(code));
+    return NanEscapeScope(err);
+}
+
 v8::Handle<v8::Value> ParseMetadata(const grpc_metadata_array *metadata_array);
 
 class PersistentHolder {

src/node/ext/server.cc

@@ -235,7 +235,7 @@ NAN_METHOD(Server::RequestCall) {
       new struct tag(new NanCallback(args[0].As<Function>()), ops.release(),
                      shared_ptr<Resources>(nullptr)));
   if (error != GRPC_CALL_OK) {
-    return NanThrowError("requestCall failed", error);
+    return NanThrowError(nanErrorWithCode("requestCall failed", error));
   }
   CompletionQueueAsyncWorker::Next();
   NanReturnUndefined();