ocs_doc_api: layer CRUD, per-curve layer assignment, XDATA/XRECORD support, and bulk SetXDataMany

crates/ocs_doc_api/examples/e5_failure_and_guards.rs

@@ -54,10 +54,7 @@ fn main() -> ocs_doc_api::ApiResult<()> {
     }
 
     // A totally unknown id also surfaces a structured error.
-    assert!(matches!(
-        doc.entities().get(ObjectId::from_u64(0xDEAD)),
-        Err(_)
-    ));
+    assert!(doc.entities().get(ObjectId::from_u64(0xDEAD)).is_err());
     println!("failure semantics verified");
     Ok(())
 }