Basically, yaws_compile was unable to process items in some "unlucky"
paths on Win32.
NTFS may generate filenames in an MS-DOS compatible format if the
original filename is not compatible with the legacy 8.3 notation;
these filenames often contain tilde characters, which are inserted
(unquoted) in the Format parameter of io:format by the string
These unquoted tilde characters are processed as usual, leading to
a badarg error as the Data parameter is always an empty list.