More fixes

server-rs/src/data/postcodes.rs

@@ -128,6 +128,7 @@ impl PostcodeData {
                     // Compute centroid across all vertices from all rings
                     let total_vertices: usize = rings.iter().map(|ring| ring.len()).sum();
                     let centroid = if total_vertices == 0 {
+                        tracing::warn!(postcode = %postcode, "Postcode polygon has zero vertices, defaulting centroid to (0,0)");
                         (0.0, 0.0)
                     } else {
                         let mut sum_lat: f32 = 0.0;