Fix pathname parsing for tracked files (#5008)

The trackedModified call in the tracking logic has a bug that
incorrectly removes `null` from pathnames

Currently:
```
let pathname = parsed.href.replace(parsed.hash, '').replace(parsed.search, '')
```
Where if `parsed.hash` or `parsed.search` are missing (which is
mostly the case for FS files), the value is null
eg `{ hash: null, search: null}`
  - In which case, we essentially trim `null`
converting `/mypath/nulldir/file.js` -> `/mypath/dir/filejs` and
breaking builds (see #4920 ).

Fix checks if `hash` or `search` are set before replacing them

Fixes #4920

Author: peteretelej

src/jit/lib/setupContextUtils.js

@@ -379,7 +379,8 @@ function trackModified(files, fileModifiedMap) {
     if (!file) continue
 
     let parsed = url.parse(file)
-    let pathname = parsed.href.replace(parsed.hash, '').replace(parsed.search, '')
+    let pathname = parsed.hash ? parsed.href.replace(parsed.hash, '') : parsed.href
+    pathname = parsed.search ? pathname.replace(parsed.search, '') : pathname
     let newModified = fs.statSync(decodeURIComponent(pathname)).mtimeMs
 
     if (!fileModifiedMap.has(file) || newModified > fileModifiedMap.get(file)) {