Check whether instruction is None before attempting execution

kernel/modelverse_kernel/main.py

@@ -57,6 +57,8 @@ class ModelverseKernel(object):
 
         if phase_v == "finish":
             gen = self.helper_init(user_root)
+        elif inst is None:
+            raise Exception("Instruction pointer could not be found!")
         elif isinstance(phase_v, string_types):
             if phase_v == "init" and inst in self.compiled:
                 #print("%-30s(%s)" % ("COMPILED " + str(self.primitives[inst]), phase_v))
@@ -439,7 +441,7 @@ class ModelverseKernel(object):
                                    ("RDE", [user_frame, "returnvalue"]),
                                    ("CNV", ["finish"]),
                                   ]
-
+        print("Resolved to " + str(variable))
         _, _, _, _ =        yield [("CD", [user_frame, "phase", new_phase]),
                                    ("CD", [user_frame, "returnvalue", variable]),
                                    ("DE", [phase_link]),