Skip structure detection on preprocessor failure

Change-Id: I679ff2045ab0ac5da64e72d87e0c78054369da5c

internal/ceres/solver.cc

diff --git a/internal/ceres/solver.cc b/internal/ceres/solver.cc
index b72661c..611e465 100644
--- a/internal/ceres/solver.cc
+++ b/internal/ceres/solver.cc
@@ -773,7 +773,7 @@
   // modified_options.linear_solver_type because, depending on the
   // lack of a Schur structure, the preprocessor may change the linear
   // solver type.
-  if (IsSchurType(pp.linear_solver_options.type)) {
+  if (status && IsSchurType(pp.linear_solver_options.type)) {
     // TODO(sameeragarwal): We can likely eliminate the duplicate call
     // to DetectStructure here and inside the linear solver, by
     // calling this in the preprocessor.