A setting row whose value column is empty or NULL (seen on some migrated databases) was parsed directly, so getInt/getBool and the GetAllSetting reflection path crashed with 'strconv.Atoi: parsing "": invalid syntax'. This made the Inbounds page (/defaultSettings -> GetPageSize) and the Settings page fail to load.
Treat an empty stored value the same as a missing row and fall back to the built-in default at the int/bool parse sites. String getters are unchanged, so legitimately-empty string settings stay empty.
Closes#4830