npe error

Exception in thread "main" org.apache.spark.SparkException: Exception thrown in awaitResult: 
	at org.apache.spark.util.ThreadUtils$.awaitResult(ThreadUtils.scala:205)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4$$anonfun$6.apply(CrossValidator.scala:164)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4$$anonfun$6.apply(CrossValidator.scala:164)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:33)
	at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:186)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
	at scala.collection.mutable.ArrayOps$ofRef.map(ArrayOps.scala:186)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4.apply(CrossValidator.scala:164)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4.apply(CrossValidator.scala:144)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:33)
	at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:186)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
	at scala.collection.mutable.ArrayOps$ofRef.map(ArrayOps.scala:186)
	at org.apache.spark.ml.tuning.CrossValidator.fit(CrossValidator.scala:144)
	at biggis.landuse.spark.examples.rasterframeclassification$.delayedEndpoint$biggis$landuse$spark$examples$rasterframeclassification$1(rasterframeclassification.scala:114)
	at biggis.landuse.spark.examples.rasterframeclassification$delayedInit$body.apply(rasterframeclassification.scala:35)
	at scala.Function0$class.apply$mcV$sp(Function0.scala:34)
	at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
	at scala.App$$anonfun$main$1.apply(App.scala:76)
	at scala.App$$anonfun$main$1.apply(App.scala:76)
	at scala.collection.immutable.List.foreach(List.scala:392)
	at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35)
	at scala.App$class.main(App.scala:76)
	at biggis.landuse.spark.examples.rasterframeclassification$.main(rasterframeclassification.scala:35)
	at biggis.landuse.spark.examples.rasterframeclassification.main(rasterframeclassification.scala)
Caused by: java.lang.NullPointerException: Value at index 0 is null
	at org.apache.spark.sql.Row$class.getAnyValAs(Row.scala:472)
	at org.apache.spark.sql.Row$class.getDouble(Row.scala:248)
	at org.apache.spark.sql.catalyst.expressions.GenericRow.getDouble(rows.scala:166)
	at org.apache.spark.ml.classification.Classifier.getNumClasses(Classifier.scala:115)
	at org.apache.spark.ml.classification.DecisionTreeClassifier.train(DecisionTreeClassifier.scala:102)
	at org.apache.spark.ml.classification.DecisionTreeClassifier.train(DecisionTreeClassifier.scala:45)
	at org.apache.spark.ml.Predictor.fit(Predictor.scala:118)
	at org.apache.spark.ml.Predictor.fit(Predictor.scala:82)
	at org.apache.spark.ml.Pipeline$$anonfun$fit$2.apply(Pipeline.scala:153)
	at org.apache.spark.ml.Pipeline$$anonfun$fit$2.apply(Pipeline.scala:149)
	at scala.collection.Iterator$class.foreach(Iterator.scala:891)
	at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
	at scala.collection.IterableViewLike$Transformed$class.foreach(IterableViewLike.scala:44)
	at scala.collection.SeqViewLike$AbstractTransformed.foreach(SeqViewLike.scala:37)
	at org.apache.spark.ml.Pipeline.fit(Pipeline.scala:149)
	at org.apache.spark.ml.Pipeline.fit(Pipeline.scala:96)
	at org.apache.spark.ml.Estimator.fit(Estimator.scala:61)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4$$anonfun$5$$anonfun$apply$1.apply$mcD$sp(CrossValidator.scala:152)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4$$anonfun$5$$anonfun$apply$1.apply(CrossValidator.scala:151)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4$$anonfun$5$$anonfun$apply$1.apply(CrossValidator.scala:151)
	at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
	at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
	at org.spark_project.guava.util.concurrent.MoreExecutors$SameThreadExecutorService.execute(MoreExecutors.java:293)
	at scala.concurrent.impl.ExecutionContextImpl$$anon$1.execute(ExecutionContextImpl.scala:136)
	at scala.concurrent.impl.Future$.apply(Future.scala:31)
	at scala.concurrent.Future$.apply(Future.scala:494)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4$$anonfun$5.apply(CrossValidator.scala:160)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4$$anonfun$5.apply(CrossValidator.scala:150)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:33)
	at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:186)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
	at scala.collection.mutable.ArrayOps$ofRef.map(ArrayOps.scala:186)
	at org.apache.spark.ml.tuning.CrossValidator$$anonfun$4.apply(CrossValidator.scala:150)
	... 19 more