Fix crash on invalid smart playlist

src/smart-parser.c

@@ -55,11 +55,11 @@ typedef struct tag_sp_node {
     } right;
 } SP_NODE;
 
-
-#define SP_OPTYPE_ANDOR  0
-#define SP_OPTYPE_STRING 1
-#define SP_OPTYPE_INT    2
-#define SP_OPTYPE_DATE   3
+#define SP_OPTYPE_INVALID 0
+#define SP_OPTYPE_ANDOR   1
+#define SP_OPTYPE_STRING  2
+#define SP_OPTYPE_INT     3
+#define SP_OPTYPE_DATE    4
 
 #define SP_HINT_NONE      0
 #define SP_HINT_STRING    1