narrow down C# test error

src/kiss/EmbeddedScript.hx

@@ -211,7 +211,9 @@ class EmbeddedScript {
                             // fields, otherwise DSL state will be lost when forking, which is unacceptable
                             var fork = new kiss.cloner.Cloner().clone(this);
                             fork.instructions[instructionPointer] = command;
-                            // trace(fork.breakPoints);
+                            if (fork.breakPoints == null) {
+                                throw 'cloning failed';
+                            }
                             // trace('running a fork from ' + Std.string(instructionPointer + 1));
                             fork.run();
                             // trace("fork finished");

src/kiss/cloner/Cloner.hx

@@ -39,7 +39,7 @@ class Cloner {
             return v;
         #end
 
-        #if neko
+        #if (neko || cs)
         try {
             if (Type.getClassName(cast v) != null)
                 return v;
@@ -68,7 +68,7 @@ class Cloner {
             case TEnum(e):
                 return v;
             case TUnknown:
-                return null;
+                throw 'Cannot clone object of unknown type $v';
         }
     }