1 files changed, 14 insertions, 0 deletions
diff --git a/src/Comm.c b/src/Comm.c
index de81a2a..b601982 100644
--- a/src/Comm.c
+++ b/src/Comm.c
@@ -80,6 +80,10 @@ int PUGH_SyncGroup(const cGH *GH, const char *groupname)
                 "PUGH_SyncGroup: Unknown group: %s", groupname);
     retval = -1;
   }
+  else if (CCTK_NumVarsInGroupI(group) == 0)
+  {
+    /* do nothing */
+  }
   else
   {
     CCTK_GroupData(group, &pgroup);
@@ -295,6 +299,8 @@ static int PUGH_SyncGArrayGroup(pGH *pughGH, int first_var)
   pGA *firstGA;
 
 
+  if (first_var<0 || first_var>=CCTK_NumVars()) CCTK_WARN (0, "internal error");
+
   firstGA = (pGA *) pughGH->variables [first_var][0];
 
 #ifdef DEBUG_PUGH
@@ -971,6 +977,14 @@ static int PUGH_SyncSingleProc(pGH *pughGH, pComm *comm)
 
   GA = (pGA *) pughGH->variables [comm->first_var][comm->sync_timelevel];
 
+  /* return if no storage assigned */
+  if (! GA->storage)
+  {
+    CCTK_VWarn(2, __LINE__, __FILE__, CCTK_THORNSTRING,
+               "Trying to synchronize variable '%s' with no storage", GA->name);
+    return;
+  }
+
   /* since we need to iterators here we need to allocate one */
   iterator_from = GA->extras->iterator;
   iterator_to = (int *) malloc (GA->extras->dim * sizeof (int));