update error message for num_chains/num_threads

Author: SteveBronder

src/cmdstan/arguments/arg_num_chains.hpp

@@ -10,6 +10,11 @@ class arg_num_chains : public int_argument {
   arg_num_chains() : int_argument() {
     _name = "num_chains";
     _description = std::string("Number of chains");
+    _validity = "num_chains > 0";
+    _default = "1";
+    _constrained = true;
+    _good_value = 2.0;
+    _bad_value = 0.0;
     _default = "1";
     _default_value = 1;
     _value = _default_value;

src/cmdstan/arguments/arg_num_threads.hpp

@@ -10,8 +10,12 @@ class arg_num_threads : public int_argument {
   arg_num_threads() : int_argument() {
     _name = "num_threads";
     _description = std::string("Number of threads available to the program.");
+    _validity = "num_threads > 0 || num_threads == -1";
     _default = "1";
     _default_value = 1;
+    _good_value = 1.0;
+    _bad_value = -2.0;
+    _constrained = true;
     _value = _default_value;
   }
 #ifdef STAN_THREADS