diff --git a/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts b/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts
index 60d5c680e9a..3fd56961ac0 100644
--- a/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts
+++ b/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts
@@ -494,15 +494,18 @@ const processDiscoveredFragments = (
   fieldMap: NodeAndDefCollection,
   discoveredFragments: Array<Array<string>>,
 ) => {
-  while (discoveredFragments.length !== 0) {
-    const item = discoveredFragments.pop();
+  let item;
+  while ((item = discoveredFragments.pop()) !== undefined) {
+    const [fragmentName, referencedFragmentName] = item;
     if (
-      !item ||
-      comparedFragmentPairs.has(item[1], item[0], areMutuallyExclusive)
+      comparedFragmentPairs.has(
+        referencedFragmentName,
+        fragmentName,
+        areMutuallyExclusive,
+      )
     ) {
       continue;
     }
-    const [fragmentName, referencedFragmentName] = item;
     comparedFragmentPairs.add(
       referencedFragmentName,
       fragmentName,