How can I investigate cases where php.exe crashes on startup in an Azure App Service with no stdout/stderr output?

I'm trying to install ImageMagick on an Azure App Service instance running WordPress. The Azure App Service is running PHP 7.3.3 x64 otherwise fine.

1. I went to this web-page to get the right zips to download: https://mlocati.github.io/articles/php-windows-imagick.html
2. phpinfo() says I'm running PHP 7.3.3 x64 MSVC15 non-thread-safe, so I downloaded:
   • php_imagick-3.4.3-7.3-nts-vc15-x64.zip
   • ImageMagick-7.0.7-11-vc15-x64.zip
3. I extracted the two zip files into their own respective subdirectories in D:\home\site\ext directory.
4. I created an empty file at D:\home\site\ext\extensions.ini.
5. In the Azure App Service configuration area, I added the environment variable PHP_INI_SCAN_DIR=D:\home\site\ext\.
6. In extensions.ini I put this single line: extension=D:\home\site\ext\php_imagick-3.4.3-7.3-nts-vc15-x64\php_imagick.dll.
7. Then I restarted the Azure App Service. Since then PHP crashes immediately on startup.

8. To investigate I opened Kudu and ran the PHP command-line interface from the wwwroot directory:

   cd D:\home\site\wwwroot\
   php -f phpinfo.php
   

   • This causes PHP to crash immediately. It writes nothing to standard-output nor stderr (so running php -f phpinfo.php > out.txt 2> err.txt gives me zero-byte files out.txt and err.txt).
   • My global php.ini already has display_errors = On and display_startup_errors = On.
9. Nothing is logged anywhere in Azure other than that the FastCGI Extension exited unexpectedly.
10. After commenting out the #extension=D:\home\site\ext... line PHP works fine.

I'm assuming this might be an issue with a missing system dependency (such as VisualC++ Redistributables) but Azure claims all current VisualC++ Redistributables are pre-installed (and we can't install our own anyway).

Is there any way to investigate a process-crash-on-startup?

I know one option is WinDbg, but I don't know how to get a crash dump in an Azure App Service.