[8.0.5602.0] Update check fails for imported userscripts without @updateURL if source file is moved or deleted

### Please answer the following questions for yourself before submitting an issue

- [x] Filters were updated before reproducing an issue
- [x] I checked the [knowledge base](https://adguard.com/kb/) and found no answer
- [x] I checked to make sure that this issue has not already been filed

### AdGuard version

8.0.5602.0 aka 8.0.0 nightly 60 (5602)

### Browser version

151.0.7922.174

### OS version

Windows 11 Pro X64 25H2 26200.x

### Traffic filtering

- [x] yes, I do

### Ad Blocking

_No response_

### Privacy

_No response_

### Social

_No response_

### Annoyances

_No response_

### Security

_No response_

### Other

_No response_

### Language-specific

_No response_

### Which DNS server do you use?

System default DNS

### DNS protocol

None

### Custom DNS

_No response_

### What Stealth Mode options do you have enabled?

_No response_

### Support ticket ID

_No response_

### Issue Details

Steps to reproduce:
1. Update to recent nightly build.
2. Add userscripts with not added lines for updates.
3. Open Update tab in AdGuard. First update will pass.
4. Reboot OS.
5. Now edit manually imported from the files UserScripts (without `UpdateURL` lines) in internal AdGuard editor.
6. AdGuard will fail

```
VERBOSE, AdguardSvc.exe, Logger, 29, 22.08.2026 21:17:32.262, AGHttpProcessingUnit handleProcessedStream: [id=1000004-h2-ssl-1] client HTTP stream is fully processed, closing
VERBOSE, AdguardSvc.exe, Logger, 29, 22.08.2026 21:17:32.262, AGHttpProcessingUnit handleProcessedStream: [id=1000004-h2-ssl-1] remote HTTP stream is fully processed, closing
VERBOSE, AdguardSvc.exe, Logger, 29, 22.08.2026 21:17:32.262, AGHttpProcessingUnit handleProcessedStream: [id=1000004-h2-ssl]] Closed
VERBOSE, AdguardSvc.exe, Logger, 29, 22.08.2026 21:17:32.262, SSLFilter tcp_packet: [id=1000004] SSLFilter::tcp_packet dd=DD_OUTPUT pd=PD_SEND m_state=SFS_DATA_EXCHANGE len=13
VERBOSE, AdguardSvc.exe, Logger, 29, 22.08.2026 21:17:32.263, SSLFilter tcp_packet: [id=1000004] SSLFilter::tcp_packet preprocessOutputData
VERBOSE, AdguardSvc.exe, Logger, 29, 22.08.2026 21:17:32.263, SSLFilter tcp_packet: [id=1000004] SSLFilter::tcp_packet dd=DD_OUTPUT pd=PD_RECEIVE m_state=SFS_DATA_EXCHANGE len=399
VERBOSE, AdguardSvc.exe, Logger, 29, 22.08.2026 21:17:32.263, SSLFilter tcp_packet: [id=1000004] SSLFilter::tcp_packet preprocessOutputData
VERBOSE, AdguardSvc.exe, Logger, 29, 22.08.2026 21:17:32.263, SSLFilter tcp_packet: [id=1000004] SSLFilter::tcp_packet dd=DD_OUTPUT pd=PD_RECEIVE m_state=SFS_DATA_EXCHANGE len=9
VERBOSE, AdguardSvc.exe, Logger, 29, 22.08.2026 21:17:32.263, SSLFilter tcp_packet: [id=1000004] SSLFilter::tcp_packet preprocessOutputData
WARNING, AdguardSvc.exe, Logger, 24, 22.08.2026 21:17:32.264, Error while checking userscript updates: System.InvalidOperationException: Cannot check userscript's "D:/fademind/Desktop/js_/NoAutoPlay.user.js" update because of an error (error code is -1)
Source: Adguard.Core
Stack trace: at Adguard.Core.Userscripts.UserscriptParser.IsUpdateAvailable(String version, String updateUrl)
at WrGs7mBslJDPEYawqCA9.jKyBvC8gNE0(Object , String , String , WrGs7mBslJDPEYawqCA9 )
at Adguard.Service.Userscripts.UserscriptParserService.IsUpdateAvailable(String version, String updateUrl)
at Adguard.Service.Userscripts.UserscriptService.EcY7yKp4xFg(String , String , Boolean& )

.
VERBOSE, AdguardSvc.exe, Logger, 24, 22.08.2026 21:17:32.264, UpdateUserscript: isUpdateAvailable=False, isUpdateCheckSuccessful=False
WARNING, AdguardSvc.exe, Logger, 24, 22.08.2026 21:17:32.264, Cannot check userscript NoAutoPlay update: System.Exception: Userscript update check failed
Source: Adguard.Service
Stack trace: at Adguard.Service.Userscripts.UserscriptService.UpdateUserscript(UserscriptInfo userscript)

WARNING, AdguardSvc.exe, Logger, 24, 22.08.2026 21:17:32.264, Can't check userscript update: NoAutoPlay. Error: System.Exception: Userscript update check failed
Source: Adguard.Service
Stack trace: at Adguard.Service.Userscripts.UserscriptService.UpdateUserscript(UserscriptInfo userscript)
at Adguard.Service.Userscripts.UserscriptService.UpdateUserscripts(Boolean forced)

```

### Expected Behavior

Ignore updates for local only imported UserScripts without `UpdateURL`

### Actual Behavior

Fail update local only UserScripts

### Screenshots

Screenshot 1

### Additional Information

Regression GH-6093

```
// ==UserScript==
// @name NoAutoPlay
// @namespace http://tampermonkey.net/
// @version 2.7
// @description Blocks automatic video/audio playback. Playback only after clicking (shadow-DOM aware, re-strips autoplay attribute on reappearance). Also fixes redgifs.com opening a new tab when clicking embedded videos from reddit.com.
// @match *://*/*
// @run-at document-start
// @grant none
// @icon https://i.imgur.com/MTbo09w.png
// ==/UserScript==
(function () {
'use strict';

```

```
// ==UserScript==
// @name YouTube Force Quality
// @description Force 720p / 1080p / 2K / 4K / Max
// @version 2.0.4
// @match https://www.youtube.com/*
// @match https://m.youtube.com/*
// @run-at document-start
// @noframes
// @icon https://t1.gstatic.com/faviconV2?client=SOCIAL&type=FAVICON&fallback_opts=TYPE,SIZE,URL&url=http://youtube.com&size=64
// ==/UserScript==

(function () {
'use strict';

```