More useful error message

src/one-body-sample.cc

@@ -302,7 +302,8 @@ int main(int argc, char *argv[]) {
             break;
 
           if (state_fpi == state_fpi_max)
-            std::cerr << "FPI did not converge after " << state_fpi_max
+            std::cerr << "[ref = " << refinements
+                      << "]: FPI did not converge after " << state_fpi_max
                       << " iterations" << std::endl;
         }
         if (parset.get<bool>("printProgress"))