Skip events with no PVs in SV fit.

cuda/vertex_fit/vertex_fitter/src/VertexFitter.cu

@@ -292,8 +292,9 @@ __global__ void fit_secondary_vertices(
   const ParKalmanFilter::FittedTrack* event_tracks = dev_kf_tracks + event_tracks_offset;
 
   // Primary vertices.
+  const uint n_pvs_event = *(dev_number_of_multi-fit_vertices + event_number);
   gsl::span<PV::Vertex const> vertices {dev_multi_fit_vertices + event_number * PV::max_number_vertices,
-                                        *(dev_number_of_multi_fit_vertices + event_number)};
+                                        n_pvs_event};
   
   // Secondary vertices.
   VertexFit::TrackMVAVertex* event_secondary_vertices = dev_secondary_vertices + sv_offset;
@@ -310,8 +311,8 @@ __global__ void fit_secondary_vertices(
 
     // Don't fit SVs in events with no PVs.
     // TODO: Decide how to handle events with no PVs.
-    if (pv_table.size == 0) return;
-
+    if (n_pvs_event == 0) return;
+    
     const ParKalmanFilter::FittedTrack trackA = event_tracks[i_track];
 
     // Preselection on first track.