Fix an issue where None speaker label can cause sunburst and treemap charts unbuildable

Plotly's sunburst and treemap require all ids to be non-null strings. But calcSpeakingTypes in sonogram_utility.py is producing it. Fix update to filter the None speaker.

utils.py

@@ -168,6 +168,19 @@ def build_df5(oneVoice, multiVoice, sumNoVoice, sumOneVoice, sumMultiVoice, curr
     multiSpeakerList = list(multiSpeakerList) if multiSpeakerList else []
     multiTimeList    = list(multiTimeList)    if multiTimeList    else []
 
+    # Filter out None/empty speaker labels — these come from annotationToNoiseList
+    # when a time window has no identified speaker. Plotly silently drops or
+    # crashes on None ids, causing the entire chart to disappear.
+    ov_pairs = [(s, t) for s, t in zip(speakerList, timeList)
+                if s is not None and str(s).strip() != ""]
+    speakerList = [p[0] for p in ov_pairs]
+    timeList    = [p[1] for p in ov_pairs]
+
+    mv_pairs = [(s, t) for s, t in zip(multiSpeakerList, multiTimeList)
+                if s is not None and str(s).strip() != ""]
+    multiSpeakerList = [p[0] for p in mv_pairs]
+    multiTimeList    = [p[1] for p in mv_pairs]
+
     summativeMulti = sum(multiTimeList) if multiTimeList else 1
     safeOneVoice   = sumOneVoice if sumOneVoice > 0 else 1