[bug] Browser rendering fails when using @reown_appkit-siwx in Vite + React

[yungyoseo]

Link to minimal reproducible example

https://github.com/yungyoseo/siwx-test.git

Steps to Reproduce

1. Create a Vite + React + TypeScript project.
2. Install @reown/appkit/react, @reown/appkit-siwx, @reown/appkit-adapter-wagmi, wagmi, @tanstack/react-query.
3. Copy the AppKitProvider code and include siwx: new DefaultSIWX() in createAppKit.
4. Run the dev server and open the project in a browser.
5. UI fails to render; console shows:
   Uncaught TypeError: Cannot read properties of undefined (reading 'slice')
   at readable-stream/_stream_writable.js:57

Summary

Expected Behavior:

• AppKitProvider initializes correctly and app renders normally.

Actual Behavior:

• Adding siwx: new DefaultSIWX() causes AppKitProvider initialization to fail.
• App does not render, console shows:
  Uncaught TypeError: Cannot read properties of undefined (reading 'slice')
  at readable-stream/_stream_writable.js:57
• Removing siwx fixes the issue.

List of related npm package versions

npm list

├── @coinbase/cdp-sdk@1.38.6
├── @eslint/js@9.39.1
├── @reown/appkit-adapter-wagmi@1.8.14
├── @reown/appkit-siwx@1.8.14
├── @reown/appkit@1.8.14
├── @tanstack/react-query@5.90.10
├── @types/node@24.10.1
├── @types/react-dom@19.2.3
├── @types/react@19.2.6
├── @vitejs/plugin-react-swc@4.2.2
├── eslint-plugin-react-hooks@7.0.1
├── eslint-plugin-react-refresh@0.4.24
├── eslint@9.39.1
├── globals@16.5.0
├── react-dom@19.2.0
├── react@19.2.0
├── typescript-eslint@8.47.0
├── typescript@5.9.3
├── viem@2.39.3
├── vite@7.2.4
└── wagmi@3.0.1

Node.js Version

v24.0.0

Package Manager

npm@11.6.2

[linear]

APKT-4294