fix(manager): restore template preview image when creating document

[Ibochkarev]

What does it do?

• Adds getPreviewPath() and getPreviewSourceId() to modElement so the template list can pass a filesystem path and media source id to phpThumb instead of a URL.
• Updates Template/GetList to build the template preview phpThumb URL using path + source; phpThumb’s default source (Flysystem) expects a path, so passing a URL caused blank output.
• In modMediaSource::prepareSrcForThumb(), converts local HTTP URLs (matching the site base URL) to filesystem paths before the fileExists() check, so callers that still pass URLs (e.g. subdirectory installs) continue to work.
• In the PhpThumb processor: fixes PHP 8.1 deprecation when pathinfo(..., PATHINFO_EXTENSION) returns null (guard with is_string($ext) before strtolower($ext)), and removes error_reporting(E_ALL) so deprecations do not corrupt the image response.

Why is it needed?

Template preview images did not render when creating a new document (Create document → template picker): the preview URL pointed at phpThumb with src set to a full URL. The default media source uses Flysystem, which expects a path; fileExists($url) failed and the processor returned empty output. In subdirectory installs the image path was also wrong. PHP 8.1+ triggered a deprecation for strtolower(null) and error_reporting(E_ALL) caused that to appear in the image body.

How to test

1. Create a template with a preview image (Template → Preview Image, e.g. under assets/images/ or a media source).
2. Open Create document; in the template picker, select a template that has a preview.
3. Confirm the preview image loads (no white/blank area).
4. With MODX in a subdirectory (base_url e.g. /subdir/), repeat and confirm the preview still loads.
5. Call phpThumb with a file that has no extension (or empty extension) and confirm no PHP deprecation in the response.

Related issue(s)/PR(s)

Resolves #16256

[biz87]

Code Review

Summary

Fixes template preview images when creating documents. Adds getPreviewPath() and getPreviewSourceId() to modElement to provide filesystem paths (instead of URLs) to phpThumb. Updates Template/GetList to use these new methods. Adds URL-to-path conversion in modMediaSource::prepareSrcForThumb() for subdirectory installs. Removes error_reporting(E_ALL) from the PhpThumb processor and fixes a PHP 8.1 deprecation (pathinfo returning null).

Suggestions

• modElement.php: getPreviewPath() and getPreviewSourceId() share significant logic (fetching source, initializing, checking basePath + previewfile). Consider extracting the shared source resolution into a private helper to reduce duplication.
• modMediaSource.php:1585-1607: The URL-to-filesystem conversion in prepareSrcForThumb() does file_exists() checks — ensure this doesn't introduce a performance concern when called frequently (e.g. in a large template list), since file_exists() hits the filesystem on each call.

Assessment

Solid fix addressing a real issue with phpThumb expecting filesystem paths rather than URLs. The PhpThumb processor cleanup (removing error_reporting(E_ALL), guarding pathinfo return) is a good improvement. The is_string($ext) guard before strtolower() properly handles PHP 8.1 deprecations. Multi-file change is well-coordinated across the stack.

Verdict: Approve