-#define EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION 1
-#define EVAL_ERROR_UNKNOWN_OPERAND 2
-#define EVAL_ERROR_MISSING_OPERAND 3
-#define EVAL_ERROR_MISSING_OPERATOR 4
-#define EVAL_ERROR_REMAINING_GARBAGE 5
+#define EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION 1
+#define EVAL_ERROR_UNKNOWN_OPERAND 2
+#define EVAL_ERROR_MISSING_OPERAND 3
+#define EVAL_ERROR_MISSING_OPERATOR 4
+#define EVAL_ERROR_REMAINING_GARBAGE 5
+#define EVAL_ERROR_IF_THEN_ELSE_MISSING_ELSE 6