get_sub_app_mut is now an Option

in [9202](https://github.com/StarArawn/bevy_ecs_tilemap/pull/bevyengine/bevy/pull/9202) SubApp access has changed

Author: ChristopherBiscardi

src/render/material.rs

@@ -116,7 +116,7 @@ where
     }
 
     fn finish(&self, app: &mut App) {
-        if let Ok(render_app) = app.get_sub_app_mut(RenderApp) {
+        if let Some(render_app) = app.get_sub_app_mut(RenderApp) {
             render_app
                 .add_render_command::<Transparent2d, DrawTilemapMaterial<M>>()
                 .init_resource::<MaterialTilemapPipeline<M>>()

src/render/mod.rs

@@ -212,8 +212,8 @@ impl Plugin for TilemapRenderingPlugin {
         );
 
         let render_app = match app.get_sub_app_mut(RenderApp) {
-            Ok(render_app) => render_app,
-            Err(_) => return,
+            Some(render_app) => render_app,
+            None => return,
         };
 
         render_app.init_resource::<TilemapPipeline>();