UI crashes when loading ruleset fails

[matthias-ronge]

java.lang.NullPointerException
    at org.kitodo.production.forms.createprocess.CreateProcessForm.getAllRulesetDivisions(CreateProcessForm.java:113)
    at org.kitodo.production.forms.createprocess.CreateProcessForm.updateRulesetAndDocType(CreateProcessForm.java:100)
    at org.kitodo.production.forms.createprocess.CreateProcessForm.prepareProcess(CreateProcessForm.java:356)

The reason is that if an error occurs while reading the ruleset, the exception is caught and the object remains uninitialized. Then an attempt is made to access the object. In addition, only the exception message is logged, without a stack trace, so that the error cannot be traced:

[ERROR] 2021-01-05 09:57:49.133 [http-nio-8080-exec-7] CreateProcessForm - null

Furthermore, the code is named unsystematically at the point. The ruleset management is sometimes referred to as the ruleset and sometimes as the ruleset management interface. The names should be standardized.