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# EvaluatorError

A value that describes why an evaluator failed while scoring a produced subject.

```
enum EvaluatorError
```

## Overview

The evaluation runner records these values in the `"EvaluatorErrors"` column of
[`detailed`](/documentation/Evaluations/EvaluationResult/detailed) as an array. Multiple evaluators can fail for the same
sample. The evaluation runner omits this column entirely when no evaluator fails,
so check for the column’s presence before reading it.

```swift
let result = try await evaluation.run()
if result.detailed.containsColumn("EvaluatorErrors") {
    let column = result.detailed["EvaluatorErrors", [EvaluatorError].self]
    for (index, failures) in column.enumerated() {
        if let failures {
            for failure in failures {
                print("Sample \(index): \(failure.localizedDescription)")
            }
        }
    }
}
```

Rows with an `EvaluatorErrors` value always have a non-`nil` `Response`. Evaluators
only run after subject production succeeds. Distinct from
[`SubjectInferenceError`](/documentation/Evaluations/SubjectInferenceError), which covers failures that occur before subject production.

## Topics

### Enumeration Cases

[`case failed(evaluator: (any EvaluatorProtocol)?, evaluatorType: String, reason: String)`](/documentation/Evaluations/EvaluatorError/failed(evaluator:evaluatorType:reason:))

The evaluator threw an error while scoring the subject.

## Relationships

### Conforms To

[`SendableMetatype`](/documentation/Swift/SendableMetatype)

[`LocalizedError`](/documentation/Foundation/LocalizedError)

[`Sendable`](/documentation/Swift/Sendable)

[`Error`](/documentation/Swift/Error)

---

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