diff --git a/crates/engine/src/commands/track.rs b/crates/engine/src/commands/track.rs
index 928bf63b..77cb7494 100644
--- a/crates/engine/src/commands/track.rs
+++ b/crates/engine/src/commands/track.rs
@@ -214,7 +214,7 @@ fn create(s: &mut Session, p: &V, cmd: &str) -> Result<V> {
         let mut ids = Ids(&mut next);
         let g = tracking::tracker(&mut ids, &name, st, &pts);
         let uid = g.uid;
-        l.motion_trackers_mut(&mut ids).children.push(g.into());
+        l.motion_trackers_mut(&mut ids).ok_or_else(|| bad(cmd, "the layer has no Motion Trackers group"))?.children.push(g.into());
         proj.next_id = next;
         state.current_track = Some((lid, uid));
         state.selected_layers = vec![lid];
diff --git a/crates/project/src/lib.rs b/crates/project/src/lib.rs
index 2771c65e..a2e85089 100644
--- a/crates/project/src/lib.rs
+++ b/crates/project/src/lib.rs
@@ -4,6 +4,8 @@
 //! ([`props`]). Compositions sit behind `Arc` so undo snapshots share everything that did not
 //! change.
 
+#![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]
+
 pub mod build;
 pub mod essential;
 pub mod props;
diff --git a/crates/project/src/tracking.rs b/crates/project/src/tracking.rs
index 5e7f8f1d..cc344793 100644
--- a/crates/project/src/tracking.rs
+++ b/crates/project/src/tracking.rs
@@ -235,11 +235,11 @@ impl Layer {
         self.trackers().find(|(g, _)| g.uid == uid)
     }
     /// The Motion Trackers group, created (first in the layer's tree, like AE) when missing.
-    pub fn motion_trackers_mut(&mut self, ids: &mut Ids) -> &mut PropGroup {
+    pub fn motion_trackers_mut(&mut self, ids: &mut Ids) -> Option<&mut PropGroup> {
         if self.props.sub(MOTION_TRACKERS).is_none() {
             self.props.children.insert(0, motion_trackers(ids).into());
         }
-        self.props.sub_mut(MOTION_TRACKERS).expect("motion trackers group")
+        self.props.sub_mut(MOTION_TRACKERS)
     }
 }