fix(workaround): multipart subscriptions that terminate with payload: null (#11594)

* fix(workaround): multipart subscriptions that terminate with payload: null

* Clean up Prettier, Size-limit, and Api-Extractor

Author: alessbell

.changeset/little-squids-watch.md

@@ -0,0 +1,5 @@
+---
+"@apollo/client": patch
+---
+
+Adds a fix for multipart subscriptions that terminate with payload: null

.size-limits.json

@@ -1,4 +1,4 @@
 {
-  "dist/apollo-client.min.cjs": 39229,
-  "import { ApolloClient, InMemoryCache, HttpLink } from \"dist/index.js\" (production)": 32616
+  "dist/apollo-client.min.cjs": 39245,
+  "import { ApolloClient, InMemoryCache, HttpLink } from \"dist/index.js\" (production)": 32630
 }

src/link/http/__tests__/HttpLink.ts

@@ -1940,6 +1940,10 @@ describe("HttpLink", () => {
         "Content-Type: application/json",
         "",
         '{"payload":{"data":{"aNewDieWasCreated":{"die":{"color":"blue","roll":2,"sides":5}}}}}',
+        "---",
+        "Content-Type: application/json",
+        "",
+        '{"payload": null}',
         "-----",
       ].join("\r\n");
 

src/link/http/parseAndCheckHttpResponse.ts

@@ -84,6 +84,9 @@ export async function readMultipartBody<
           if (isApolloPayloadResult(result)) {
             let next = {};
             if ("payload" in result) {
+              if (Object.keys(result).length === 1 && result.payload === null) {
+                return;
+              }
               next = { ...result.payload };
             }
             if ("errors" in result) {