Beta1 worked fine for me. RC1 only does "KCrash: Application 'filelight' crashing...".
I tried removing filelightrc, with no success. Pointing towards a specific dir also didn't produce anything else. This is under Gentoo ~x86.
Same problem as parent, with a little more output:
QMultiInputContext::changeInputMethod(): index=0, slave=xim
QPainter::begin: Cannot paint null pixmap
QPainter::setPen: Will be reset by begin()
KCrash: Application 'filelight' crashing...
And the output with --enable-debug:
filelight: FSTAB: auto
filelight: FSTAB: ntfs
filelight: FSTAB: proc
filelight: FSTAB: swap
filelight: FSTAB: vfat
filelight: FSTAB: ext2
QMultiInputContext::changeInputMethod(): index=0, slave=xim
filelight: >> bool RadialMap::Map::resize(const QRect&)
filelight: >> void RadialMap::Map::make(const Directory*, bool)
filelight: >> void RadialMap::Map::setRingBreadth()
filelight: >> void RadialMap::Map::colorise()
filelight: >> void RadialMap::Map::paint(unsigned int)
QPainter::begin: Cannot paint null pixmap
QPainter::setPen: Will be reset by begin()
KCrash: Application 'filelight' crashing...