Error handling

src/Root/SkinDetectorWriter.h

@@ -16,6 +16,7 @@ public:
     virtual ~SkinDetectorWriter();
 
     void add(int detID, float p_x, float p_y, float p_z, float m_x, float m_y, float m_z);
+    int status() { return i_status; }
     void write();
     void close();
 
@@ -23,6 +24,7 @@ private:
     TFile* t_file;
     TTree* t_tree;
     TClonesArray* t_buffer;
+    int i_status;
 };