Undefined 'code' TypeError within errorNormalize
When running Apollo Server 4.10.1, I am running into an unhandled TypeError where extensions is undefined, so the error code cannot be retrieved from the object.

Here is the diff that solved my problem:

```diff
diff --git a/node_modules/@apollo/server/src/errorNormalize.ts b/node_modules/@apollo/server/src/errorNormalize.ts
index 55efdde..ecdb82d 100644
--- a/node_modules/@apollo/server/src/errorNormalize.ts
+++ b/node_modules/@apollo/server/src/errorNormalize.ts
@@ -60,11 +60,13 @@ export function normalizeAndFormatErrors(
 
     const extensions: GraphQLErrorExtensions = {
       ...graphqlError.extensions,
-      code:
-        graphqlError.extensions.code ??
-        ApolloServerErrorCode.INTERNAL_SERVER_ERROR,
+      code: ApolloServerErrorCode.INTERNAL_SERVER_ERROR,
     };
 
+    if (graphqlError && graphqlError.extensions && graphqlError.extensions.code) {
+      extensions.code = graphqlError.extensions.code;
+    }
+
     if (isPartialHTTPGraphQLHead(extensions.http)) {
       mergeHTTPGraphQLHead(httpFromErrors, {
         headers: new HeaderMap(),
```