[MOA] NullPointerException using OpenmlTaskEvaluator

Reproduce the failure with the two openml.OpenmlDataStreamClassification commands, then inspect moa.evaluation.LearningEvaluation.java at line 53 and moa.tasks.openml.OpenmlDataStreamClassification.java at line 175. Compare the OpenmlTaskEvaluator path with BasicClassificationPerformanceEvaluator. Done means the reported task configurations complete without the NullPointerException.

From @DraXus on February 15, 2015 18:20

I got the following error when running tasks in MOA (last version from OpenML website).

I tried different tasks and configurations:
openml.OpenmlDataStreamClassification -t 2177 -e openml.OpenmlTaskEvaluator
openml.OpenmlDataStreamClassification -l functions.NoChange -t 2172 -e openml.OpenmlTaskEvaluator

Failure reason: null
*** STACK TRACE ***java.lang.NullPointerException
    at java.util.Arrays$ArrayList.<init>(Arrays.java:2842)
    at java.util.Arrays.asList(Arrays.java:2828)
    at moa.evaluation.LearningEvaluation.<init>(LearningEvaluation.java:53)
    at moa.tasks.openml.OpenmlDataStreamClassification.doMainTask(OpenmlDataStreamClassification.java:175)
    at moa.tasks.MainTask.doTaskImpl(MainTask.java:50)
    at moa.tasks.AbstractTask.doTask(AbstractTask.java:57)
    at moa.tasks.TaskThread.run(TaskThread.java:76)

In addition, the console log output looks fine without errors:

[15-02-2015 18:11:27] [OK] [Authenticate] Authentication successfull. 
[15-02-2015 18:11:28] [INFO] [ARFF Cache] Stored dataset dataset_4_labor.arff to cache. 
[15-02-2015 18:11:28] [OK] [Download] Obtained Stream Header. 

However, it works if BasicClassificationPerformanceEvaluator is selected instead.

Copied from original issue: openml/OpenML#173