chore: import upstream snapshot with attribution

tools/challenge-helper-scripts/helpers/utils.ts

@@ -0,0 +1,19 @@
+export function insertInto<T>(arr: T[], index: number, elem: T): T[] {
+  if (index >= arr.length) return [...arr, elem];
+  if (index <= 0) return [elem, ...arr];
+
+  return arr.flatMap((x, id) => {
+    return id === index ? [elem, x] : x;
+  });
+}
+
+// fs Promise functions return errors, but no stack trace.  This adds back in
+// the stack trace.
+export function withTrace<Args extends unknown[], Result>(
+  fn: (...x: Args) => Promise<Result>,
+  ...args: Args
+): Promise<Result> {
+  return fn(...args).catch((reason: Error) => {
+    throw Error(reason.message);
+  });
+}