refactor deletion of cache tags header

Author: sommeeeer

packages/open-next/src/adapters/middleware.ts

@@ -129,9 +129,6 @@ const defaultHandler = async (
         result.headers[INTERNAL_EVENT_REQUEST_ID] = requestId;
       }
 
-      // Can safely delete this header here before returning as it is only used for the cache tags internally
-      delete result.headers["x-next-cache-tags"];
-
       debug("Middleware response", result);
       return result;
     },

packages/open-next/src/utils/cache.ts

@@ -39,7 +39,10 @@ export function getTagsFromValue(value?: CacheValue<"cache">) {
   }
   // The try catch is necessary for older version of next.js that may fail on this
   try {
-    return value.meta?.headers?.["x-next-cache-tags"]?.split(",") ?? [];
+    const cacheTags =
+      value.meta?.headers?.["x-next-cache-tags"]?.split(",") ?? [];
+    delete value.meta?.headers?.["x-next-cache-tags"];
+    return cacheTags;
   } catch (e) {
     return [];
   }