[node] Handle tiles which 404 better

include/mbgl/storage/response.hpp

@@ -7,7 +7,7 @@ namespace mbgl {
 
 class Response {
 public:
-    enum Status : bool { Error, Successful };
+    enum Status { Error, Successful, NotFound };
 
     Status status = Error;
     std::string message;

platform/node/src/node_request.cpp

@@ -64,7 +64,9 @@ NAN_METHOD(NodeRequest::Respond) {
     auto resource = std::move(nodeRequest->resource);
 
     if (info.Length() < 1) {
-        return Nan::ThrowTypeError("First argument must be an error object");
+        auto response = std::make_shared<mbgl::Response>();
+        response->status = mbgl::Response::NotFound;
+        source->notify(*resource, response);
     } else if (info[0]->BooleanValue()) {
         auto response = std::make_shared<mbgl::Response>();
 

src/mbgl/map/raster_tile_data.cpp

@@ -33,6 +33,12 @@ void RasterTileData::request(float pixelRatio,
     req = fs->request({ Resource::Kind::Tile, url }, util::RunLoop::getLoop(), [url, callback, this](const Response &res) {
         req = nullptr;
 
+        if (res.status == Response::NotFound) {
+            state = State::parsed;
+            callback();
+            return;
+        }
+
         if (res.status != Response::Successful) {
             std::stringstream message;
             message <<  "Failed to load [" << url << "]: " << res.message;

src/mbgl/map/vector_tile_data.cpp

@@ -44,6 +44,12 @@ void VectorTileData::request(float pixelRatio, const std::function<void()>& call
     req = fs->request({ Resource::Kind::Tile, url }, util::RunLoop::getLoop(), [url, callback, this](const Response &res) {
         req = nullptr;
 
+        if (res.status == Response::NotFound) {
+            state = State::parsed;
+            callback();
+            return;
+        }
+
         if (res.status != Response::Successful) {
             std::stringstream message;
             message <<  "Failed to load [" << url << "]: " << res.message;