keymap: fix NULL dereference when dumping the default fallback type The default fallback type uses type->level_names = NULL but the keymap-dump code was not checking this case. Instead of adding more workarounds and possible bugs (e.g. previous commit), let's just keep the number of level names separately. This has the additional advantage retains extraneous level name if someone adds them for some reason. Signed-off-by: Ran Benita <ran234@gmail.com>