Various crash fixes.

src/pathfinding.rs

@@ -1,6 +1,7 @@
 use std::collections::HashMap;
 
 use bevy::{
+    ecs::entity::Entities,
     prelude::*,
     tasks::{prelude::*, Task},
 };
@@ -258,9 +259,15 @@ fn poll_tasks(mut commands: Commands, mut query: Query<(Entity, &mut Calculating
     }
 }
 
-fn remove_destination(mut commands: Commands, removed: RemovedComponents<Destination>) {
+fn remove_destination(
+    mut commands: Commands,
+    entities: &Entities,
+    removed: RemovedComponents<Destination>,
+) {
     for entity in removed.iter() {
-        commands.entity(entity).remove::<Calculating>();
+        if entities.contains(entity) {
+            commands.entity(entity).remove::<Calculating>();
+        }
     }
 }
 

src/visibility.rs

@@ -314,19 +314,20 @@ fn remove_visible(
                 continue;
             }
             visible_entities.remove(&removed);
-            let map = map.single();
-            let mut cache = HashMap::new();
-            viewshed.update(
-                &viewer_entity,
-                &mut visible_entities,
-                start,
-                &*query_pipeline,
-                &collider_query,
-                map,
-                &visible,
-                &mut cache,
-                &mut changed,
-            );
+            if let Ok(map) = map.get_single() {
+                let mut cache = HashMap::new();
+                viewshed.update(
+                    &viewer_entity,
+                    &mut visible_entities,
+                    start,
+                    &*query_pipeline,
+                    &collider_query,
+                    map,
+                    &visible,
+                    &mut cache,
+                    &mut changed,
+                );
+            }
         }
     }
 }