add error message when a scene is undefined

src/cmd.rs

@@ -748,6 +748,11 @@ fn spawn_scenes(
     for state_wrapper in er_spawnscene.read() {
         let root_state = &state_wrapper.0;
 
+        let mut found = false;
+        let scene_name = root_state
+            .name
+            .clone()
+            .unwrap_or_else(|| String::from("ERROR_NO_SCENE_NAME"));
         let scene_defs = include!("data/scenes.in");
         for (name, template, pos, rot) in scene_defs {
             let pos = DVec3::new(
@@ -755,7 +760,8 @@ fn spawn_scenes(
                 root_state.pos[1] + pos[2],
                 root_state.pos[2] - pos[1],
             );
-            if Some(name.to_string()) == root_state.name {
+            if name == scene_name {
+                found = true;
                 let mut state = ParserState::default();
                 state.class = DefClass::Actor;
                 state.pos = pos;
@@ -902,6 +908,9 @@ fn spawn_scenes(
                 }
             }
         }
+        if !found {
+            error!("Undefined scene `{}'", scene_name);
+        }
     }
 }