On a large Moodle site we host when you access this url :-

/course/report/log/index.php?id=1

You get just this message :-

Choose which logs you want to see:

NO FOOTER or SELECTOR DROPDOWNS shown

Error log doesn't show any details with Debugging on All.

Replication steps:

1. Run the report on a site with data.
2. Limit the memory for the report adding this line after the requires

   ini_set('memory_limit', "30000000");

3. Should give you the limited output, if the page is giving 500 increase the memory or if it is working lower the memory.