final null check on stateLoadCallBack (#1411)

Signed-off-by: Adam Warner <me@adamwarner.co.uk>

scripts/pi-hole/js/messages.js

@@ -99,6 +99,11 @@ $(function () {
     },
     stateLoadCallback: function () {
       var data = utils.stateLoadCallback("messages-table");
+      // Return if not available
+      if (data === null) {
+        return null;
+      }
+
       // Reset visibility of ID and blob columns
       var hiddenCols = [0, 4, 5, 6, 7, 8];
       for (var key in hiddenCols) {