Move prefetch bailout to start of the prefetch function for pages (#…

…43731)

Found that prefetching bails later than it has to in development for `pages`. This moves it to be the first thing that is checked in prefetch()


## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see [`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] [e2e](https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs) tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see [`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm build && pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

packages/next/shared/lib/router/router.ts

@@ -2267,6 +2267,11 @@ export default class Router implements BaseRouter {
     asPath: string = url,
     options: PrefetchOptions = {}
   ): Promise<void> {
+    // Prefetch is not supported in development mode because it would trigger on-demand-entries
+    if (process.env.NODE_ENV !== 'production') {
+      return
+    }
+
     if (typeof window !== 'undefined' && isBot(window.navigator.userAgent)) {
       // No prefetches for bots that render the link since they are typically navigating
       // links via the equivalent of a hard navigation and hence never utilize these
@@ -2361,11 +2366,6 @@ export default class Router implements BaseRouter {
       }
     }
 
-    // Prefetch is not supported in development mode because it would trigger on-demand-entries
-    if (process.env.NODE_ENV !== 'production') {
-      return
-    }
-
     const data =
       process.env.__NEXT_MIDDLEWARE_PREFETCH === 'strict'
         ? ({} as any)