изменение способа работы с Null элементами в ValueXMLSchema

[kinnder]

[ERROR] 2021-12-22 23:23:11.782 [main] PlanCommand - java.lang.NullPointerException: Cannot invoke "Object.toString()" because "value" is null at application.storage.xml.ValueXMLSchema.combine(ValueXMLSchema.java:47) ~[application-0.2.0.jar:?] at application.storage.xml.ActionParametersXMLSchema.combine(ActionParametersXMLSchema.java:60) ~[application-0.2.0.jar:?] at application.storage.xml.SystemOperationXMLSchema.combine(SystemOperationXMLSchema.java:53) ~[application-0.2.0.jar:?] at application.storage.xml.SystemProcessXMLSchema.combine(SystemProcessXMLSchema.java:35) ~[application-0.2.0.jar:?] at application.storage.xml.SystemProcessXMLSchema.combine(SystemProcessXMLSchema.java:10) ~[application-0.2.0.jar:?] at application.storage.xml.XMLFile.save(XMLFile.java:61) ~[application-0.2.0.jar:?] at application.storage.xml.XMLFile.save(XMLFile.java:53) ~[application-0.2.0.jar:?] at application.storage.PersistanceStorage.saveSystemProcess(PersistanceStorage.java:88) ~[application-0.2.0.jar:?] at application.Application.saveSystemProcess(Application.java:103) ~[application-0.2.0.jar:?] at application.command.PlanCommand.execute(PlanCommand.java:31) ~[application-0.2.0.jar:?] at application.command.PlanCommand.execute(PlanCommand.java:18) ~[application-0.2.0.jar:?] at application.command.Command.run(Command.java:26) [application-0.2.0.jar:?] at application.Application.run(Application.java:173) [application-0.2.0.jar:?] at application.Main.main(Main.java:12) [application-0.2.0.jar:?]