When the method: OIFitsChecker.isInspectRules() has been added in the code to catch failures, we can go into methods with null values.
To prevent this problem a number of checks (on values that can be null) have been created:

if (value == null) {
}

In this case on FitsImageLoader, we propose to initialize the values to a default value so that it can not be null anymore and ensure all mandatory keywords in memory have a not null value (getters should never return null)