Fix LT-22110: Intermittent crash in Segment.get_AnalysesRS (#325)

Author: jtmaxwell3

src/SIL.LCModel/DomainServices/AnalysisGuessServices.cs

@@ -402,6 +402,7 @@ private IDictionary<IAnalysis, Dictionary<IAnalysis, PriorityCount>> GetAnalysis
 			var segs = new HashSet<ISegment>();
 			foreach (ISegment seg in wordform.OccurrencesInTexts)
 			{
+				if (!seg.IsValidObject) continue;
 				if (segs.Contains(seg)) continue;
 				segs.Add(seg);
 				for (int i = 0; i < seg.AnalysesRS.Count; i++)
@@ -462,6 +463,7 @@ private Dictionary<IAnalysis, Dictionary<IAnalysis, PriorityCount>> GetGlossCoun
 				return counts;
 			foreach (ISegment seg in analysis.Wordform.OccurrencesInTexts)
 			{
+				if (!seg.IsValidObject) continue;
 				if (segs.Contains(seg)) continue;
 				segs.Add(seg);
 				for (int i = 0; i < seg.AnalysesRS.Count; i++)
@@ -732,6 +734,8 @@ private IWfiWordform GetLowercaseWordform(AnalysisOccurrence occurrence, int ws,
 				return null;
 			if (onlyIndexZeroLowercaseMatching && occurrence.Index != 0)
 				return null;
+			if (occurrence.Segment == null || !occurrence.Segment.IsValidObject)
+				return null;
 			ITsString tssWfBaseline = occurrence.BaselineText;
 			var cf = new CaseFunctions(Cache.ServiceLocator.WritingSystemManager.Get(ws));
 			string sLower = cf.ToLower(tssWfBaseline.Text);

src/SIL.LCModel/DomainServices/AnalysisOccurrence.cs

@@ -56,7 +56,7 @@ public virtual IAnalysis Analysis
 		{
 			get
 			{
-				if (Segment?.AnalysesRS != null && Index < Segment.AnalysesRS.Count)
+				if (Segment != null && Segment.IsValidObject && Segment.AnalysesRS != null && Index < Segment.AnalysesRS.Count)
 					return Segment.AnalysesRS[Index];
 				return null;
 			}