fader_form_event library Null safety

Classes

ChangedFaderAnimationMilliseconds
ChangedFaderAppId
ChangedFaderBackground
ChangedFaderConditions
ChangedFaderDescription
ChangedFaderDocumentID
ChangedFaderImageSeconds
ChangedFaderItems
FaderFormEvent
InitialiseFaderFormEvent
InitialiseFaderFormNoLoadEvent
InitialiseNewFaderFormEvent