Prevent no attribute error when using Mtcnn

Author: MattPChoy

deepface/detectors/FastMtCnn.py

@@ -44,7 +44,7 @@ def detect_faces(
         detections = self.model.detect(
             img_rgb, landmarks=True
         )  # returns boundingbox, prob, landmark
-        if len(detections[0]) > 0:
+        if detections is not None and len(detections) > 0:
 
             for current_detection in zip(*detections):
                 x, y, w, h = xyxy_to_xywh(current_detection[0])

deepface/detectors/MtCnn.py

@@ -46,7 +46,7 @@ def detect_faces(
         img_rgb = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)  # mtcnn expects RGB but OpenCV read BGR
         detections = self.model.detect_faces(img_rgb)
 
-        if len(detections) > 0:
+        if detections is not None and len(detections) > 0:
 
             for current_detection in detections:
                 x, y, w, h = current_detection["box"]