♻️ refactor: Hoist postcondition check.

Author: make-github-pseudonymous-again

src/kahn1962.js

@@ -19,8 +19,4 @@ export default function* kahn1962(queue, graph) {
 			}
 		}
 	}
-
-	if (graph.size > 0) {
-		throw new Error('kahn: graph has at least one cycle');
-	}
 }

src/sorted.js

@@ -9,8 +9,9 @@ import kahn1962 from './kahn1962.js';
  * @param {Iterable<any>} edges - The input graph as a list of edges.
  * @param {Function} breakTies - The function to break ties.
  * @returns {Iterable<any>} The vertices sorted in topological order.
+ * @throws {Error} If the input graph contains a cycle.
  */
-export default function sorted(edges, breakTies = undefined) {
+export default function* sorted(edges, breakTies = undefined) {
 	const graph = Pairs.from(edges);
 
 	const queue = breakTies ? new Heap(breakTies) : [];
@@ -19,5 +20,11 @@ export default function sorted(edges, breakTies = undefined) {
 	for (const [, v] of graph) freeVertices.delete(v);
 	for (const u of freeVertices) queue.push(u);
 
-	return kahn1962(queue, graph);
+	yield* kahn1962(queue, graph);
+
+	if (graph.size > 0) {
+		throw new Error(
+			'@aureooms/js-topological-sorting#sorted: input graph contains a cycle',
+		);
+	}
 }