xai-org/x-algorithm · error · NoSuchElementException

collection is empty

Error message

collection is empty

What it means

Min.apply throws NoSuchElementException("collection is empty") when the input collection is empty, since min stays null after iterating. Same semantics as Max and standard empty-aggregate behavior.

Source

Thrown at botmaker/src/java/com/twitter/botmaker/function/math/Min.java:58

  public Signature getSignature() {
    return SIGNATURE;
  }

  @Override
  protected CacheLevel getCacheLevel() {
    return CacheLevel.Global;
  }

  @Override
  protected Object apply(Context<Runtime> context, List<Number> numbers) {
    Number min = null;
    for (Number num : numbers) {
      if (min == null || num.doubleValue() < min.doubleValue()) {
        min = num;
      }
    }
    if (min == null) {
      throw new NoSuchElementException("collection is empty");
    }
    return min;
  }
}

View on GitHub (pinned to 24c60942c5)

Solutions

1. Guard with an emptiness check and supply a default (e.g. If(IsEmpty(list), default, Min(list)))
2. Ensure upstream filters/windows guarantee at least one element
3. Catch NoSuchElementException only as a last resort at pipeline level

Example fix

// before
Number m = Min().apply(ctx, numbers); // empty -> NoSuchElementException
// after
Number m = numbers.isEmpty() ? Double.MAX_VALUE : (Number) Min().apply(ctx, numbers);

if (numbers == null || numbers.isEmpty()) {
  return DEFAULT_VALUE;
}
return Min().apply(ctx, numbers);

public static boolean nonEmpty(Collection<?> c) { return c != null && !c.isEmpty(); }

try {
  return (Number) Min().apply(ctx, numbers);
} catch (NoSuchElementException e) {
  return emptyDefault;
}

When it happens

Trigger: Calling Min() with an empty collection: Min().apply(ctx, ImmutableList.of()), or an expression computing a minimum over an empty window/group.

Common situations: Empty time windows, empty filter results, optional/nullable lists evaluated to empty, off-by-one range boundaries.

Related errors

• collection is empty
• cannot pass empty collection to Foldl1()
• Invalid numeric type (%s)
• expecting a non-negative number for Sqrt() function but rece

AI-assisted analysis of xai-org/x-algorithm@24c60942c5 (2026-08-28). Data as JSON: /api/errors/b39a9d9b67297485. Report an issue: GitHub.