setting arrayofStacks to the last stack from the cloned array. If that is undefined as well then setting it to an empty array

lib/helpers.js

@@ -614,7 +614,7 @@ function searchDiscriminator(searchObj, searchValue, swaggerSpec, parentObj, arr
               let clonedStacks = _.cloneDeep(arrayofStacks);
               for (let i = 0; i < arrayVal.length; i++) {
                 if (arrayofStacks[i] === null || arrayofStacks[i] === undefined) {
-                  arrayofStacks[i] = clonedStacks[i - 1];
+                  arrayofStacks[i] = clonedStacks.length ? clonedStacks[clonedStacks.length - 1] : [];
                 }
                 arrayofStacks[i].push(`${i}`);
               }