Describe the bug

The default theme-provider.tsx generated by the shadcn preset contains a ThemeHotkey component that attaches a global keydown listener via window.addEventListener. During browser autofill/autocomplete on Chrome and Edge, the browser fires a synthetic keydown event where event.key is undefined. The listener calls event.key.toLowerCase() without a null-check, causing an uncaught TypeError.

Affected component/components

Input

How to reproduce

• Create a new Next.js project using the shadcn preset (npx shadcn@latest init)
• Use the default generated theme-provider.tsx (no modifications)
• Add a plain to any page
• Save an autofill entry in Chrome or Edge for that field
• Focus the input and select a suggestion from the browser autocomplete dropdown

Current Behavior:

Uncaught TypeError: Cannot read properties of undefined (reading 'toLowerCase')
    at onKeyDown (theme-provider.tsx)

Expected Behavior:
No error. The autofill completes normally and the theme hotkey listener safely ignores events with an undefined key.

Root Cause:
In theme-provider.tsx

//  Crashes when event.key is undefined (browser autofill synthetic event)
if (event.key.toLowerCase() !== 'd') {
  return;
}

Codesandbox/StackBlitz link

No response

Logs

System Info

Next.js:   16.2.3
Node.js:   20x
pnpm:      9.15.9
OS:        Windows 10
Browser:   Chrome / Edge (Firefox working without any error)
Repro:     Plain <input type="email" /> with no custom hooks

Before submitting

• I've made research efforts and searched the documentation
• I've searched for existing issues