Today we debugged an error message coming from XmlFileLoader in the DI component:

File some.xml does not contain valid XML, it is empty.

Coming from

The file is not empty :) removing the @ reveals the true error:

PHP Warning:  file_get_contents(file.ext): failed to open stream: Permission denied 

So if $content is false (before trim casts to string) we cant assume an empty file. Ideally the original errors bubbles up.