Fixed SMART data is null bug

web/SystemAO/disk/smart/smart.html

@@ -74,7 +74,7 @@
           $.getJSON("/system/disk/smart/getSMART", function(data) {
                 smartDATA = data;
                 $("#mainmenu").html("");
-                if ($(data).length == 0) {
+                if (data == null || $(data).length == 0) {
                     $("#smart-holder").append(append("-1","No disk find!","",-1));
                     $("#healthy").text("No disks detected.");
                     $("#totaldisk").text("0");