Fixes for when not using persistance feature

egui/src/memory.rs

@@ -23,7 +23,6 @@ pub struct Memory {
     /// This will be saved between different program runs if you use the `persistence` feature.
     ///
     /// To store a state common for all your widgets (a singleton), use [`Id::null`] as the key.
-    #[cfg(feature = "persistence")]
     pub data: crate::util::IdAnyMap,
 
     // ------------------------------------------

egui/src/util/id_any_map.rs

@@ -60,6 +60,7 @@ struct SerializedElement {
     ron: String,
 }
 
+#[cfg(feature = "persistence")]
 type Serializer = fn(&Box<dyn Any + 'static + Send + Sync>) -> Option<String>;
 
 enum Element {