Remove redundant validation check

We already check that all half-edges are connected by identical surface
vertices. Checking the surface on top of that is redundant.

crates/fj-kernel/src/objects/cycle.rs

@@ -24,20 +24,14 @@ impl Cycle {
     pub fn new(half_edges: impl IntoIterator<Item = Handle<HalfEdge>>) -> Self {
         let half_edges = half_edges.into_iter().collect::<Vec<_>>();
 
-        let surface = match half_edges.first() {
-            Some(half_edge) => half_edge.surface().clone(),
-            None => panic!("Cycle must contain at least one half-edge"),
-        };
-
-        // Verify, that the curves of all edges are defined in the correct
-        // surface.
-        for edge in &half_edges {
-            assert_eq!(
-                surface.id(),
-                edge.curve().surface().id(),
-                "Edges in cycle not defined in same surface"
-            );
-        }
+        // This is not a validation check, and thus not part of the validation
+        // infrastructure. The property being checked here is inherent to the
+        // validity of a `Cycle`, as methods of `Cycle` might assume that there
+        // is at least one edge.
+        assert!(
+            !half_edges.is_empty(),
+            "Cycle must contain at least one half-edge"
+        );
 
         if half_edges.len() != 1 {
             // Verify that all edges connect.