node-server

What version of Hono are you using? : 4.11.7 : 1.19.9 What runtime/OS are you seeing the problem on? Bun 1.2.19 (Linux) Also reproduced on Node.js v22.17.1 What steps can reproduce the bug? When 's runs with (the default), it replaces and with lightweight polyfills. Libraries that validate objects via or break silently because the objects returned by native were constructed with the original classes, not Hono's replacements. Minimal reproduction with : Upstream mock (any server returning JSON on ). Trigger: Bun test proving the issue What is the expected behavior? should not break checks in third-party libraries. Returning the same / object from middleware callbacks should work regardless of . What do you see instead? internally validates middleware returns with: The object returned by native was constructed with the original class, but after , checks against Hono's replacement polyfill — which fails. Root cause 's replaces and with lightweight alternatives. Any library relying on or to validate objects created by the native will break, because native fetch constructs objects using the original constructors, not the replacements. Additional context This affects any library that uses or for validation, not just . The pattern is common in HTTP middleware ecosystems (, , custom fetch wrappers, etc.).