add safeguards

Author: h-mayorquin

src/spikeinterface/extractors/nwbextractors.py

@@ -764,6 +764,8 @@ def _fetch_recording_segment_info_backend(self, file, cache, load_time_vector, s
             timestamps = electrical_series["timestamps"][:]
             t_start = timestamps[0]
             sampling_frequency = 1.0 / np.median(np.diff(timestamps[:samples_for_rate_estimation]))
+        else:
+            raise ValueError("TimeSeries must have either starting_time or timestamps")
 
         if load_time_vector and timestamps is not None:
             times_kwargs = dict(time_vector=electrical_series["timestamps"])
@@ -1573,6 +1575,8 @@ def _fetch_recording_segment_info(self, file, cache, load_time_vector, samples_f
             timestamps = timeseries.timestamps
             sampling_frequency = 1.0 / np.median(np.diff(timestamps[:samples_for_rate_estimation]))
             t_start = timestamps[0]
+        else:
+            raise ValueError("TimeSeries must have either starting_time or timestamps")
 
         if load_time_vector and timestamps is not None:
             times_kwargs = dict(time_vector=timestamps)