DAQ: fix bug in facedetection if result is None.

src/aare/daq/daq.py

@@ -49,7 +49,7 @@ from aare.common.automation_models import (
 from aare.common.raster_grid import RasterGridRequest, CompletedRasterGrid, CompletedRasterGridElem, grid_to_image_id
 from aare.common.rotation_scan import RotationScanRequest, CompletedRotationScan
 from aare.common.sample_geometry import SampleGeometryModel
-from aare.daq.operations.face_detection import FaceDetectionContext, FaceDetectionService
+from aare.daq.operations.face_detection import FaceDetectionContext, FaceDetectionService, FaceDetectionResult
 from aare.daq.operations.loop_centering import LoopCenteringService, LoopCenteringContext
 from aare.daq.operations.loop_centering.models import LoopCenteringSettings
 
@@ -545,10 +545,17 @@ class AareDAQ:
             FaceDetectionResult
         """
         self.__set_state(BeamlineStateEnum.SampleAlignment)
-        result = None
+        result: FaceDetectionResult | None = None
 
         try:
-            self.__aare.send_sample_event(self.sample, SampleEventType.LOOPFACEDETECTING)
+            try:
+                sample = self.sample
+            except Exception:
+                sample = None
+
+            aare = getattr(self, "_AareDAQ__aare", None)
+            if aare is not None:
+                aare.send_sample_event(sample, SampleEventType.LOOPFACEDETECTING)
 
             result = self._create_face_detection_service().run(
                 steps=steps,
@@ -556,30 +563,55 @@ class AareDAQ:
                 face_min_ratio=face_min_ratio,
             )
 
-            if not result.success and report_error:
-                self._handle_operation_error(
-                    operation=DAQOperation.FACE_CENTERING,
-                    sample=self.sample,
-                    error=result.error or Exception("Face detection failed"),
-                    event_type=SampleEventType.LOOPFACEDETECTFAILED,
-                    additional_comment=result.comment,
-                )
-                return False
+            if not result.success:
+                if report_error:
+                    self._handle_operation_error(
+                        operation=DAQOperation.FACE_CENTERING,
+                        sample=sample,
+                        error=result.error or Exception("Face detection failed"),
+                        event_type=SampleEventType.LOOPFACEDETECTFAILED,
+                        additional_comment=result.comment,
+                    )
+                return result
 
-            self.__aare.send_sample_event(self.sample, SampleEventType.LOOPFACEDETECTED)
+            if aare is not None:
+                aare.send_sample_event(sample, SampleEventType.LOOPFACEDETECTED)
             return result
 
         except Exception as e:
             logger.error(f"Face detection failed: {e}")
             additional_comment = f"{e}" if e is not None else ""
-            self._handle_operation_error(
-                operation=DAQOperation.FACE_CENTERING,
-                sample=self.sample,
+
+            try:
+                sample = self.sample
+            except Exception:
+                sample = None
+
+            if report_error:
+                self._handle_operation_error(
+                    operation=DAQOperation.FACE_CENTERING,
+                    sample=sample,
+                    error=e,
+                    event_type=SampleEventType.LOOPFACEDETECTFAILED,
+                    additional_comment=additional_comment,
+                )
+
+            payload = (
+                result.payload
+                if result is not None
+                else {
+                    "running": False,
+                    "samples": [],
+                    "height_fit": {},
+                    "area_fit": {},
+                }
+            )
+            return FaceDetectionResult(
+                success=False,
+                payload=payload,
                 error=e,
-                event_type=SampleEventType.LOOPFACEDETECTFAILED,
-                additional_comment=additional_comment,
+                comment=additional_comment,
             )
-            return False
 
     def _execute_raster_sequence(self, grid_request: RasterGridRequest,
                                  auto_center: bool = False) -> CompletedRasterGrid | None: