require a minimum of 2 values for writing tables

src/angle_write.cpp

@@ -66,6 +66,7 @@ void AngleWrite::command(int narg, char **arg)
   int n = utils::inumeric(FLERR, arg[1], false, lmp);
   std::string table_file = arg[2];
   std::string keyword = arg[3];
+  if (n < 2) error->all(FLERR, "Must have at least 2 table values");
 
   // make sure system is initialized before calling any functions
 

src/bond.cpp

@@ -362,6 +362,7 @@ void Bond::write_file(int narg, char **arg)
   if ((inner <= 0.0) || (inner >= outer))
     error->all(FLERR, "Invalid rlo={} / rhi={} values in bond_write command.", inner, outer);
 
+  if (n < 2) error->all(FLERR, "Must have at least 2 table values");
   double r0 = equilibrium_distance(btype);
 
   // open file in append mode if exists

src/dihedral_write.cpp

@@ -69,6 +69,7 @@ void DihedralWrite::command(int narg, char **arg)
   int n = utils::inumeric(FLERR, arg[1], false, lmp);
   std::string table_file = arg[2];
   std::string keyword = arg[3];
+  if (n < 2) error->all(FLERR, "Must have at least 2 table values");
 
   // make sure system is initialized before calling any functions
 

src/pair.cpp

@@ -1806,6 +1806,8 @@ void Pair::write_file(int narg, char **arg)
   else if (strcmp(arg[3],"bitmap") == 0) style = BMP;
   else error->all(FLERR,"Invalid style in pair_write command");
 
+  if (n < 2) error->all(FLERR, "Must have at least 2 table values");
+
   double inner = utils::numeric(FLERR,arg[4],false,lmp);
   double outer = utils::numeric(FLERR,arg[5],false,lmp);
   if (inner <= 0.0 || inner >= outer)