The creation of node data called 'class' which points to a non-existent class will result in an unhandled FileNotFoundException within AdminCentral, resulting in the inability to access Magnolia.

Steps to reproduce:
WARNING: FOLLOWING THESE STEPS WILL RESULT IN THE MAGNOLIA INSTANCE BECOMING INACCESSIBLE. MANUAL MODIFICATION OF THE JCR WILL BE REQUIRED.

1. Go to 'config:/server/rendering/freemarker/templateLoaders'.
2. In this location, create a new content node called "file".
3. In the newly created content node, create node data of type "String", giving it the name "class" and the value "info.magnolia.freemarker.loaders.nonexistentClass"

From that point onwards, any attempt to access parts of AdminCentral or the web site it manages will result in unhandled exceptions.