object.isolate: an id that doesn't exist is reported as such

crates/engine/src/cmd/object.rs

@@ -859,7 +859,7 @@ fn isolate(s: &mut Session, p: &Value) -> Result<Value> {
     let st = s.doc_mut()?;
     // Groups, layers and single objects (a path, a compound path, an image…); type isn't
     // isolated: a double-click on it edits its text.
-    if st.doc.node(id).is_none_or(|n| matches!(n.kind, NodeKind::Text(_))) {
+    if matches!(st.doc.node(id).ok_or(EngineError::NoNode(id))?.kind, NodeKind::Text(_)) {
         return Err(bad("object.isolate", "type objects can't be isolated"));
     }
     let isolation = st.doc.node(id).filter(|n| n.extras().shaper.is_some()).and_then(|n| n.children()).and_then(|c| c.first()).map_or(id, |n| n.id);

crates/engine/src/tests.rs

@@ -1595,6 +1595,14 @@ fn inspect_reports_a_compound_paths_paint_and_blend_modes() {
     assert!(group["blend"] == "Multiply" && group.get("fill").is_none(), "{group}");
 }
 
+#[test]
+fn isolating_an_object_that_doesnt_exist_says_so() {
+    let mut s = session();
+    let e = s.execute("object.isolate", &json!({"id": 999_999})).unwrap_err();
+    assert_eq!(e.to_string(), EngineError::NoNode(NodeId(999_999)).to_string());
+    assert!(!e.to_string().contains("type"), "{e}");
+}
+
 /// `depth` and `childLimit` slice a summary read; a level that shows fewer children
 /// than it has reports `childCount`, and invalid values are rejected, not reinterpreted.
 #[test]