Fix:Manage Firefox and Safari Network error message (#44929)

Not all browsers implement the network error message in the same way:
For example if I execute `fetch('//foo.bar/').catch(err =>
console.log(err.message))` in Chrome / Firefox / Safari browsers
console, I get respectively:
- `Failed to fetch`
- `NetworkError when attempting to fetch resource.`
- `Load failed`

This PR fixes it.

## Bug

- [x] Related issues linked using fixes
[#45190](#45190)
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

Co-authored-by: JJ Kasper <jj@jjsweb.site>

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

@@ -791,7 +791,14 @@ function fetchNextData({
         if (!unstable_skipClientCache) {
           delete inflightCache[cacheKey]
         }
-        if (err.message === 'Failed to fetch') {
+        if (
+          // chrome
+          err.message === 'Failed to fetch' ||
+          // firefox
+          err.message === 'NetworkError when attempting to fetch resource.' ||
+          // safari
+          err.message === 'Load failed'
+        ) {
           markAssetError(err)
         }
         throw err