Use try_insert to prevent panics (#299)

* Use `try_insert` to prevent `panic`s

When using `insert` instead of `try_insert` on `EntityCommand`, it can
happen that the system panics, when the entity does not exist, even
when the `EntityCommand` has been accessed with `get_entity(...)`.
The following example demonstrates the problem:

```rust
if let Some(mut entity_commands) = commands.get_entity(entity) {
    // at this point some other system despawns `entity` concurrently
    entity_commands.insert(bundle);
    //              ^^^^^^ this will panic
}
```

This is also documented in the official bevy docs:
https://docs.rs/bevy/0.12.1/bevy/ecs/system/struct.Commands.html#method.get_entity

* replace other uses of insert with try_insert

* Update changelog

---------

Co-authored-by: Jan Riemer <[email protected]>
Co-authored-by: Aevyrie <[email protected]>

CHANGELOG.md

@@ -1,5 +1,6 @@
 # UNRELEASED
 
+- Fixed: replaced uses of `.insert` with `.try_insert`, where they could potentially panic.
 - Fixed: replace all `.single` calls with matched `.get_single` calls to avoid crashing in
   environments where there is no window available
 - Fixed: sprite picking depth is now consistent with other picking backends.

backends/bevy_picking_egui/src/lib.rs

@@ -67,7 +67,7 @@ pub fn update_settings(
                     .remove::<bevy_picking_selection::NoDeselect>(),
                 false => commands
                     .entity(entity)
-                    .insert(bevy_picking_selection::NoDeselect),
+                    .try_insert(bevy_picking_selection::NoDeselect),
             };
         }
     }

crates/bevy_picking_core/src/focus.rs

@@ -216,7 +216,7 @@ pub fn update_interactions(
         if let Ok(mut interaction) = interact.get_mut(hovered_entity) {
             *interaction = new_interaction;
         } else if let Some(mut entity_commands) = commands.get_entity(hovered_entity) {
-            entity_commands.insert(new_interaction);
+            entity_commands.try_insert(new_interaction);
         }
     }
 }

crates/bevy_picking_highlight/src/lib.rs

@@ -288,7 +288,7 @@ pub fn get_initial_highlight_asset<T: Asset>(
         match highlighting_query.get_mut(entity) {
             Ok(Some(mut highlighting)) => highlighting.initial = material.to_owned(),
             _ => {
-                commands.entity(entity).insert(InitialHighlight {
+                commands.entity(entity).try_insert(InitialHighlight {
                     initial: material.to_owned(),
                 });
             }