More informative errors in frame slicing

src/spikeinterface/core/frameslicerecording.py

@@ -27,22 +27,18 @@ class FrameSliceRecording(BaseRecording):
     def __init__(self, parent_recording, start_frame=None, end_frame=None):
         channel_ids = parent_recording.get_channel_ids()
 
-        assert parent_recording.get_num_segments() == 1, "FrameSliceRecording only works with one segment"
+        num_segments = parent_recording.get_num_segments()
+        assert num_segments == 1, f"FrameSliceRecording only works with one segment but found {num_segments}"
 
-        parent_size = parent_recording.get_num_samples(segment_index=0)
-        if start_frame is None:
-            start_frame = 0
-        else:
-            assert 0 <= start_frame < parent_size
-
-        if end_frame is None:
-            end_frame = parent_size
-        else:
-            assert (
-                0 < end_frame <= parent_size
-            ), f"'end_frame' must be fewer than number of samples in parent: {parent_size}"
+        samples_in_recording = parent_recording.get_num_samples(segment_index=0)
+        start_frame = start_frame or 0
+        end_frame = end_frame or samples_in_recording
 
-        assert end_frame > start_frame, "'start_frame' must be smaller than 'end_frame'!"
+        assert start_frame >= 0, f"{start_frame=} must be positive"
+        assert start_frame < end_frame, f"{start_frame=} must be smaller than 'end_frame' {end_frame=}!"
+        assert (
+            end_frame <= samples_in_recording
+        ), f"{end_frame=} must be smaller than or equal to {samples_in_recording=}"
 
         BaseRecording.__init__(
             self,
@@ -53,7 +49,7 @@ def __init__(self, parent_recording, start_frame=None, end_frame=None):
 
         # link recording segment
         parent_segment = parent_recording._recording_segments[0]
-        sub_segment = FrameSliceRecordingSegment(parent_segment, int(start_frame), int(end_frame))
+        sub_segment = FrameSliceRecordingSegment(parent_segment, start_frame=int(start_frame), end_frame=int(end_frame))
         self.add_recording_segment(sub_segment)
 
         # copy properties and annotations