When just loading Cractorio Base (0.2.56) and Safefill (1.0.11) I get the following error:
Failed to load mods: Error while loading mod-setting prototype "safefill-cost" (string-setting): Default value (Cheap) isn't a valid value based off the prototype limitations. Modifactions: Safe Waterfill > Cractorio Base
Going into the settings-updates.lua and changing the settings value from Cheap to cheap and Medium only to medium-only fixes the errors by making sure the string variables are exact matches for the options in Safe Waterfill