[1D] Switch to "steady mode" before attempting steady-state solve

The solver could previously get left in transient mode if an exception occurred
during time stepping, making it impossible to make a new attempt at solving the
steady-state problem.

src/oneD/OneDim.cpp

@@ -301,6 +301,10 @@ void OneDim::initTimeInteg(doublereal dt, doublereal* x)
 
 void OneDim::setSteadyMode()
 {
+    if (m_rdt == 0) {
+        return;
+    }
+
     m_rdt = 0.0;
     m_jac->updateTransient(m_rdt, m_mask.data());
 
@@ -384,10 +388,6 @@ doublereal OneDim::timeStep(int nsteps, doublereal dt, doublereal* x,
         }
     }
 
-    // Prepare to solve the steady problem.
-    setSteadyMode();
-    newton().setOptions(m_ss_jac_age);
-
     // return the value of the last stepsize, which may be smaller
     // than the initial stepsize
     return dt;

src/oneD/Sim1D.cpp

@@ -5,6 +5,7 @@
 #include "cantera/oneD/Sim1D.h"
 #include "cantera/oneD/MultiJac.h"
 #include "cantera/oneD/StFlow.h"
+#include "cantera/oneD/MultiNewton.h"
 #include "cantera/numerics/funcs.h"
 #include "cantera/base/xml.h"
 
@@ -244,6 +245,9 @@ void Sim1D::solve(int loglevel, bool refine_grid)
             writeline('.', 78, true, true);
         }
         while (!ok) {
+            // Attempt to solve the steady problem
+            setSteadyMode();
+            newton().setOptions(m_ss_jac_age);
             debuglog("Attempt Newton solution of steady-state problem...", loglevel);
             int status = newtonSolve(loglevel-1);