The assertion condition is not good when using the ‘ignoreHiddenFiles’ flag
In juce_File.cpp : 653
// you have to specify the type of files you're looking for!
// was : jassert (whatToLookFor > 0 && whatToLookFor <= 3);
jassert ((whatToLookFor & findFiles) != 0 || (whatToLookFor & findDirectories) != 0);