Ошибка: java.lang.Thread.run (Неизвестный источник) с использованием PySpark

Question

Я пытаюсь запустить этот простой наивный байесовский классификатор по PySpark:

nb = NaiveBayes(modelType='multinomial', smoothing=0.1)
model = nb.fit(dataset_test)
pred_nb = model.transform(dataset_test)

Когда я запускаю приведенный выше код, я получаю эту ошибку:

Py4JJavaError: An error occurred while calling o480.fit.
: java.util.NoSuchElementException: next on empty iterator
    at scala.collection.Iterator$$anon$2.next(Iterator.scala:39)
    at scala.collection.Iterator$$anon$2.next(Iterator.scala:37)
    at scala.collection.IndexedSeqLike$Elements.next(IndexedSeqLike.scala:63)
    at scala.collection.IterableLike$class.head(IterableLike.scala:107)
    at scala.collection.mutable.ArrayOps$ofRef.scala$collection$IndexedSeqOptimized$$super$head(ArrayOps.scala:186)
    at scala.collection.IndexedSeqOptimized$class.head(IndexedSeqOptimized.scala:126)
    at scala.collection.mutable.ArrayOps$ofRef.head(ArrayOps.scala:186)
    at org.apache.spark.sql.Dataset.head(Dataset.scala:2552)
    at org.apache.spark.ml.classification.NaiveBayes$$anonfun$trainWithLabelCheck$1.apply(NaiveBayes.scala:156)
    at org.apache.spark.ml.classification.NaiveBayes$$anonfun$trainWithLabelCheck$1.apply(NaiveBayes.scala:129)
    at org.apache.spark.ml.util.Instrumentation$$anonfun$11.apply(Instrumentation.scala:183)
    at scala.util.Try$.apply(Try.scala:192)
    at org.apache.spark.ml.util.Instrumentation$.instrumented(Instrumentation.scala:183)
    at org.apache.spark.ml.classification.NaiveBayes.trainWithLabelCheck(NaiveBayes.scala:129)
    at org.apache.spark.ml.classification.NaiveBayes.train(NaiveBayes.scala:118)
    at org.apache.spark.ml.classification.NaiveBayes.train(NaiveBayes.scala:78)
    at org.apache.spark.ml.Predictor.fit(Predictor.scala:118)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244)
    at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357)
    at py4j.Gateway.invoke(Gateway.java:282)
    at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
    at py4j.commands.CallCommand.execute(CallCommand.java:79)
    at py4j.GatewayConnection.run(GatewayConnection.java:238)
    at java.lang.Thread.run(Unknown Source)

1. О чем эта ошибка?
2. Возможно ли это исправить?