Removal of symlinked package resources fails
The File System Resource Publisher removes invalid directories or symbolic links from the _Resources/Static/Packages/ folder. This rarely happens, but it does happen if some package providing static resources is deactivated.
In that case FLOW3 failed to remove the symbolic link because the removeDirectoriesRecursively() function did not consider symlinks (only directories).
For reproducing this bug, use a TYPO3 Phoenix installation and let the TYPO3.ExtJS symlink in _Resources/Static/Packages/ point to some invalid directory. On the next web hit, FLOW3 should crash.