Fix empty pbf tile response
@@ -364,7 +364,7 @@ class EmptyResponse:
topojson.encode(out, [], (ll.lon, ll.lat, ur.lon, ur.lat), False)
elif format == 'PBF':
- pbf.encode(out, [], None, self.bounds)
+ pbf.encode(out, [], None, layer_name='')
else:
raise ValueError(format)
