Add error types and simple state

src/memory.c

@@ -40,6 +40,14 @@ struct nl_object *nl_string_create(const char *string)
     return obj;
 }
 
+struct nl_object *nl_error_create(const char *error)
+{
+    struct nl_object* obj = nl_object_alloc();
+    obj->type = NL_TYPE_ERROR;
+    obj->error = error;
+    return obj;
+}
+
 static struct nl_object* nl_object_alloc() {
     return malloc(sizeof(struct nl_object));
 }
@@ -63,6 +71,11 @@ void nl_object_delete(struct nl_object *obj) {
         case NL_TYPE_STRING:
             free((void *) obj->string);
             obj->string = NULL;
+            break;
+        case NL_TYPE_ERROR:
+            free((void *) obj->error);
+            obj->error = NULL;
+            break;
         case NL_TYPE_INT:
         case NL_TYPE_COUNT:
             break;