Scoped external-search shortcuts throw before opening provider

[dajiaohuang]

Bug report

OS information

All browsers. Reproduced in the frontend code path from main at 0f9111bcde14522af5bbc3372ed6d4a96392fe77.

Steps to reproduce

1. Enable a documentation set and select it in the search scope (for example, Git).
2. Enter a search term.
3. Press Alt + G, Alt + S, or Alt + D to search the scoped term with Google, Stack Overflow, or DuckDuckGo.

More resources

The scoped branch of Search#externalSearch reassigns a const local before opening the provider URL, so the browser raises TypeError: Assignment to constant variable and no new tab opens.

Possible fix

Use a mutable local (or construct the scoped value without reassignment) before calling $.popup.