avoid illegal free()

src/input.cpp

@@ -1913,6 +1913,7 @@ void Input::suffix()
 
     delete [] lmp->suffix;
     delete [] lmp->suffix2;
+    lmp->suffix = lmp->suffix2 = nullptr;
 
     if (strcmp(arg[0],"hybrid") == 0) {
       if (narg != 3) error->all(FLERR,"Illegal suffix command");
@@ -1927,7 +1928,6 @@ void Input::suffix()
       int n = strlen(arg[0]) + 1;
       lmp->suffix = new char[n];
       strcpy(lmp->suffix,arg[0]);
-      lmp->suffix2 = nullptr;
     }
   }
 }

src/lammps.cpp

@@ -335,7 +335,7 @@ LAMMPS::LAMMPS(int narg, char **arg, MPI_Comm communicator) :
         error->universe_all(FLERR,"Invalid command-line argument");
       delete [] suffix;
       delete [] suffix2;
-      suffix2 = NULL;
+      suffix = suffix2 = NULL;
       suffix_enable = 1;
       // hybrid option to set fall-back for suffix2
       if (strcmp(arg[iarg+1],"hybrid") == 0) {