Previously, the LVGL driver for the filesystem was initialized in the class FS. However, since 6f942e2, the order of the initializations was incorrect : the driver was initialized (FS::LVGLFileSystemInit()) before LVGL (LittleVgl.Init()), which means that the driver registration was probably dropped when LVGL was initialized.
The LVGL driver is now initialized in LittleVgl.Init(), which seems to make much more sense, since all LVGL drivers are initialized there. This way, we ensure that the initialization of the drivers is consistent.