The cause of the crash was that the `RemoveSmudge` method only invokes `SharedRandom` in the else-branch of an if condition that is only taken when the `RenderPlayer` has fog visibility on the location (locations the `RenderPlayer` can see get removed from `dirty` in `TickRender`).
To add insult to injury, the `Type` field does not even need to get set since we are only using the `Sprite` field's `null` value as a marker to be picked up by the `TickRender` method. The `Type` field is only ever used twice in `AddSmudge`, in a branch of an if-condition that will not be taken when the `Sprite` field is null, which we set explicitly. The same holds true for the `Depth` field.
30cf8c204b