If this is true, it likely means a newer version of the Entrance Aesthetic spec is being parsed, with a new type of entrance.
A developer may choose to ignore this entrance aesthetic, or display a generic entrance aesthetic, depending on their use case.
An application should NOT crash on unknown entrance aesthetics.
Checks whether this is an unknown entrance aesthetic and narrows the type to UnknownEntranceAestheticProperties if so.
If this is true, it likely means a newer version of the Entrance Aesthetic spec is being parsed, with a new type of entrance. A developer may choose to ignore this entrance aesthetic, or display a generic entrance aesthetic, depending on their use case.
An application should NOT crash on unknown entrance aesthetics.