From d19e32ccadbeabf401e1134768957558b140cdb4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fredrik=20Adel=C3=B6w?= <freben@spotify.com>
Date: Sun, 29 Mar 2026 10:30:22 +0200
Subject: [PATCH] Use duck-typing for Request check and make clarification
 best-effort
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Replace instanceof Request with a duck-type isRequestLike helper to
avoid cross-realm issues, and wrap the clarification logic in a
try/catch so it can never mask the original error.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Fredrik Adelöw <freben@spotify.com>
---
 .../ClarifyFailuresFetchMiddleware.ts         | 36 +++++++++++++------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/packages/core-app-api/src/apis/implementations/FetchApi/ClarifyFailuresFetchMiddleware.ts b/packages/core-app-api/src/apis/implementations/FetchApi/ClarifyFailuresFetchMiddleware.ts
index 46985bb244..8f63452454 100644
--- a/packages/core-app-api/src/apis/implementations/FetchApi/ClarifyFailuresFetchMiddleware.ts
+++ b/packages/core-app-api/src/apis/implementations/FetchApi/ClarifyFailuresFetchMiddleware.ts
@@ -29,22 +29,36 @@ export class ClarifyFailuresFetchMiddleware implements FetchMiddleware {
         return await next(input as any, init);
       } catch (e) {
         if (e instanceof TypeError && e.message === 'Failed to fetch') {
-          let method: string;
-          let url: string;
+          try {
+            let method: string;
+            let url: string;
 
-          if (input instanceof Request) {
-            method = input.method;
-            url = input.url;
-          } else {
-            method = init?.method || 'GET';
-            url = String(input);
+            if (isRequestLike(input)) {
+              method = input.method;
+              url = input.url;
+            } else {
+              method = init?.method || 'GET';
+              url = String(input);
+            }
+
+            e.message = `Failed to fetch: ${method} ${url}`;
+          } catch {
+            // intentionally ignored - clarification is best-effort
           }
-
-          e.message = `Failed to fetch: ${method} ${url}`;
-          throw e;
         }
         throw e;
       }
     };
   }
 }
+
+function isRequestLike(input: unknown): input is Request {
+  return (
+    input !== null &&
+    typeof input === 'object' &&
+    'method' in input &&
+    'url' in input &&
+    typeof input.method === 'string' &&
+    typeof input.url === 'string'
+  );
+}