fix: use isDefined() instead of comparing against string 'undefined'

Comparing sets[i].breakout != 'undefined' checks against the
literal string, not the undefined type. When breakout is actually
undefined, the comparison is true (different types), causing
.length to be called on undefined (TypeError). Use the existing
isDefined() helper which does typeof correctly.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: k-rister

queries/cdmq/cdm.js

@@ -3605,7 +3605,7 @@ getMetricDataSets = async function (instance, sets, yearDotMonth) {
 
   // Ensure that any breakouts are available for each set
   for (var i = 0; i < sets.length; i++) {
-    if (sets[i].breakout != 'undefined') {
+    if (isDefined(sets[i].breakout)) {
       for (var j = 0; j < sets[i].breakout.length; j++) {
         var breakout = parseBreakoutEntry(sets[i].breakout[j]).name;
         if (!setBreakouts[i].includes(breakout)) {