corrected error type

Author: Berkay Ugur Senocak

confusion_matrix.py

@@ -51,7 +51,7 @@ def process_batch(self, detections, labels: np.ndarray):
 
         try:
             detections = detections[detections[:, 4] > self.CONF_THRESHOLD]
-        except TypeError:
+        except IndexError or TypeError:
             # detections are empty, end of process
             for i, label in enumerate(labels):
                 gt_class = gt_classes[i]