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avoid-unsafe-reduce

added in: 1.18.0
warning
Pro+

Warns when the .reduce collection method is called on a potentially empty collection.

Calling .reduce on an empty collection will result in a runtime exception.

Example​

❌ Bad:

void fn() {
  final list = <int>[];
  final sum = list.reduce((a, b) => a + b); // LINT: Calling 'reduce' on an empty collection will throw an exception. Try checking if this collection is not empty first.
}

✅ Good:

void fn() {
  final list = <int>[];

  final sum = list.isEmpty ? null : list.reduce((a, b) => a + b); // Correct, has a length check first

  // OR

  if (list.isNotEmpty) {
    final sum = list.reduce((a, b) => a + b);
  }
}

Additional Resources​