-fix: handle change to collectDoubles in convertTileDriftSeriesInfoToTimeSeries

Author: ken-zlai

hub/src/main/scala/ai/chronon/hub/handlers/TimeSeriesHandler.scala

@@ -119,14 +119,18 @@ class TimeSeriesHandler(driftStore: DriftStore) {
     // check if we have a numeric / categorical feature. If the percentile drift series has non-null doubles
     // then we have a numeric feature at hand
     val isNumeric =
-      tileDriftSeries.percentileDriftSeries.asScala != null && tileDriftSeries.percentileDriftSeries.asScala
-        .exists(_ != null)
+      Option(tileDriftSeries.percentileDriftSeries).exists(series => 
+        series.asScala.exists(_ != null))
+        
     val lhsList = if (metric == NullMetric) {
-      tileDriftSeries.nullRatioChangePercentSeries.asScala
+      Option(tileDriftSeries.nullRatioChangePercentSeries).map(_.asScala).getOrElse(Seq.empty)
     } else {
-      if (isNumeric) tileDriftSeries.percentileDriftSeries.asScala
-      else tileDriftSeries.histogramDriftSeries.asScala
+      if (isNumeric) 
+        Option(tileDriftSeries.percentileDriftSeries).map(_.asScala).getOrElse(Seq.empty)
+      else 
+        Option(tileDriftSeries.histogramDriftSeries).map(_.asScala).getOrElse(Seq.empty)
     }
+    
     val points = lhsList.zip(tileDriftSeries.timestamps.asScala).map {
       case (v, ts) => TimeSeriesPoint(v, ts)
     }