This allows to have a more streamlined API for rewrites.
Since middlewares are code and not static configurations, we can allow people to
delete query params and not just overwrite them.
**⚠️ Warning ⚠️** this is a breaking change in query parameter behavior with middlewares, but the API will make more sense now. Compare the following:
```diff
import {NextResponse} from 'next/server'
export default function middleware({ nextUrl }) {
- nextUrl.searchParams.set('ignored-query-param', '');
+ nextUrl.searchParams.delete('ignored-query-param'); // 🎉
return NextResponse.rewrite(nextUrl);
}
```
Since this is breaking change, we're adding a warning every time we find a query param that is missing, and eventually--the warning will be deleted.
I don't think we need to worry about older versions of Next.js as the current behavior is misleading: merging query parameters make sense for static rewrites, but not for middlewares where you have access to all the query parameters and can manipulate them freely.
Related:
* This is the opposite of #33454
* This supersedes #33574
