Handle falsy incoming data gracefully in offsetLimitPagination().merge (#9705)

Author: shobhitsharma

CHANGELOG.md

@@ -16,6 +16,9 @@
 - Provide `@apollo/client/**/*.cjs.native.js` versions of every `@apollo/client/**/*.cjs` bundle (including dependencies `ts-invariant` and `zen-observable-ts`) to help React Native's Metro bundler automatically resolve CommonJS entry point modules. **These changes should render unnecessary [the advice we gave in the v3.5.4 section below about `metro.config.js`](#apollo-client-354-2021-11-19).** <br/>
   [@benjamn](https://github.com/benjamn) in [#9716](https://github.com/apollographql/apollo-client/pull/9716)
 
+- Handle falsy `incoming` data more gracefully in `offetLimitPagination().merge` function. <br/>
+  [@shobhitsharma](https://github.com/shobhitsharma) in [#9705](https://github.com/apollographql/apollo-client/pull/9705)
+
 ## Apollo Client 3.6.3 (tagged as `next` on npm)
 
 ### Bug Fixes

src/utilities/policies/pagination.ts

@@ -32,19 +32,23 @@ export function offsetLimitPagination<T = Reference>(
     keyArgs,
     merge(existing, incoming, { args }) {
       const merged = existing ? existing.slice(0) : [];
-      if (args) {
-        // Assume an offset of 0 if args.offset omitted.
-        const { offset = 0 } = args;
-        for (let i = 0; i < incoming.length; ++i) {
-          merged[offset + i] = incoming[i];
+
+      if (incoming) {
+        if (args) {
+          // Assume an offset of 0 if args.offset omitted.
+          const { offset = 0 } = args;
+          for (let i = 0; i < incoming.length; ++i) {
+            merged[offset + i] = incoming[i];
+          }
+        } else {
+          // It's unusual (probably a mistake) for a paginated field not
+          // to receive any arguments, so you might prefer to throw an
+          // exception here, instead of recovering by appending incoming
+          // onto the existing array.
+          merged.push.apply(merged, incoming);
         }
-      } else {
-        // It's unusual (probably a mistake) for a paginated field not
-        // to receive any arguments, so you might prefer to throw an
-        // exception here, instead of recovering by appending incoming
-        // onto the existing array.
-        merged.push.apply(merged, incoming);
       }
+
       return merged;
     },
   };