avoid segfaults in USER-MESO by checking for required atom style flags

src/USER-MESO/fix_mvv_dpd.cpp

@@ -61,6 +61,9 @@ int FixMvvDPD::setmask()
 
 void FixMvvDPD::init()
 {
+  if (!atom->vest_flag)
+    error->all(FLERR,"Fix mvv/dpd requires atom attribute vest");
+
   dtv = update->dt;
   dtf = 0.5 * update->dt * force->ftm2v;
 }

src/USER-MESO/pair_mdpd.cpp

@@ -282,6 +282,9 @@ void PairMDPD::init_style()
   if (comm->ghost_velocity == 0)
     error->all(FLERR,"Pair mdpd requires ghost atoms store velocity");
 
+  if (!atom->rho_flag)
+    error->all(FLERR,"Pair style mdpd requires atom attribute rho");
+
   // if newton off, forces between atoms ij will be double computed
   // using different random numbers
 

src/USER-MESO/pair_mdpd_rhosum.cpp

@@ -62,7 +62,11 @@ PairMDPDRhoSum::~PairMDPDRhoSum() {
  init specific to this pair style
  ------------------------------------------------------------------------- */
 
-void PairMDPDRhoSum::init_style() {
+void PairMDPDRhoSum::init_style()
+{
+  if (!atom->rho_flag)
+    error->all(FLERR,"Pair style mdpd/rhosum requires atom attribute rho");
+
   // need a full neighbor list
   int irequest = neighbor->request(this,instance_me);
   neighbor->requests[irequest]->half = 0;

src/USER-MESO/pair_tdpd.cpp

@@ -315,13 +315,17 @@ void PairTDPD::coeff(int narg, char **arg)
 void PairTDPD::init_style()
 {
   if (comm->ghost_velocity == 0)
-    error->all(FLERR,"Pair tdpd requires ghost atoms store velocity");
+    error->all(FLERR,"Pair style tdpd requires ghost atoms store velocity");
+
+  if (!atom->tdpd_flag)
+    error->all(FLERR,"Pair style tdpd requires atom properties cc/cc_flux");
 
   // if newton off, forces between atoms ij will be double computed
   // using different random numbers
 
-  if (force->newton_pair == 0 && comm->me == 0) error->warning(FLERR,
-      "Pair tdpd needs newton pair on for momentum conservation");
+  if (force->newton_pair == 0 && comm->me == 0)
+    error->warning(FLERR,"Pair tdpd needs newton pair on "
+                   "for momentum conservation");
 
   neighbor->request(this,instance_me);
 }