fix: check for None in SAS eval input (#7909)

* check for None in SAS input

* Update releasenotes/notes/check-for-None-SAS-eval-0b982ccc1491ee83.yaml

---------

Co-authored-by: David S. Batista <dsbatista@gmail.com>

haystack/components/evaluators/sas_evaluator.py

@@ -157,6 +157,9 @@ class SASEvaluator:
         if len(ground_truth_answers) != len(predicted_answers):
             raise ValueError("The number of predictions and labels must be the same.")
 
+        if any(answer is None for answer in predicted_answers):
+            raise ValueError("Predicted answers must not contain None values.")
+
         if len(predicted_answers) == 0:
             return {"score": 0.0, "individual_scores": [0.0]}
 

releasenotes/notes/check-for-None-SAS-eval-0b982ccc1491ee83.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    `SASEvaluator` now raises a `ValueError` if a `None` value is contained in the `predicted_answers` input.

test/components/evaluators/test_sas_evaluator.py

@@ -73,6 +73,21 @@ class TestSASEvaluator:
         with pytest.raises(ValueError):
             evaluator.run(ground_truth_answers=ground_truths, predicted_answers=predictions)
 
+    def test_run_with_none_in_predictions(self):
+        evaluator = SASEvaluator()
+        ground_truths = [
+            "A construction budget of US $2.3 billion",
+            "The Eiffel Tower, completed in 1889, symbolizes Paris's cultural magnificence.",
+            "The Meiji Restoration in 1868 transformed Japan into a modernized world power.",
+        ]
+        predictions = [
+            "A construction budget of US $2.3 billion",
+            None,
+            "The Meiji Restoration in 1868 transformed Japan into a modernized world power.",
+        ]
+        with pytest.raises(ValueError):
+            evaluator.run(ground_truth_answers=ground_truths, predicted_answers=predictions)
+
     def test_run_not_warmed_up(self):
         evaluator = SASEvaluator()
         ground_truths = [