Double type nullpointexception in Flink flow calculation

Flink In calculation Double How about type data Filter Filter , Use window operator function NullPointException Null pointer exception , What's going on ？

2022-05-19 09:44:22,587 WARN  org.apache.flink.runtime.taskmanager.Task                    [] - Window(TumblingEventTimeWindows(600000), EventTimeTrigger, AggregateFunction$5, PassThroughWindowFunction) (1/1)#0 (2de98fdf39aaa5e7fb973e0b4ee0168d) switched from RUNNING to FAILED with failure cause: java.io.IOException: Exception while applying AggregateFunction in aggregating state
	at org.apache.flink.runtime.state.heap.HeapAggregatingState.add(HeapAggregatingState.java:107)
	at org.apache.flink.streaming.runtime.operators.windowing.WindowOperator.processElement(WindowOperator.java:413)
	at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask$StreamTaskNetworkOutput.emitRecord(OneInputStreamTask.java:233)
	at org.apache.flink.streaming.runtime.io.AbstractStreamTaskNetworkInput.processElement(AbstractStreamTaskNetworkInput.java:134)
	at org.apache.flink.streaming.runtime.io.AbstractStreamTaskNetworkInput.emitNext(AbstractStreamTaskNetworkInput.java:105)
	at org.apache.flink.streaming.runtime.io.StreamOneInputProcessor.processInput(StreamOneInputProcessor.java:65)
	at org.apache.flink.streaming.runtime.tasks.StreamTask.processInput(StreamTask.java:496)
	at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.runMailboxLoop(MailboxProcessor.java:203)
	at org.apache.flink.streaming.runtime.tasks.StreamTask.runMailboxLoop(StreamTask.java:809)
	at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:761)
	at org.apache.flink.runtime.taskmanager.Task.runWithSystemExitMonitoring(Task.java:958)
	at org.apache.flink.runtime.taskmanager.Task.restoreAndInvoke(Task.java:937)
	at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:766)
	at org.apache.flink.runtime.taskmanager.Task.run(Task.java:575)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
	at com.chnenergy.provider.flink.FanDataFlink$5.add(FanDataFlink.java:224)
	at com.chnenergy.provider.flink.FanDataFlink$5.add(FanDataFlink.java:200)
	at org.apache.flink.runtime.state.heap.HeapAggregatingState$AggregateTransformation.apply(HeapAggregatingState.java:135)
	at org.apache.flink.runtime.state.heap.CopyOnWriteStateMap.transform(CopyOnWriteStateMap.java:373)
	at org.apache.flink.runtime.state.heap.StateTable.transform(StateTable.java:211)
	at org.apache.flink.runtime.state.heap.HeapAggregatingState.add(HeapAggregatingState.java:105)
	... 14 more

Stream data Double Type data can be transferred to 'NaN', stay Java in double as well as Double All can be received 'NaN' data , And don't throw exceptions , It is different from NULL; But the data flows into Flink Of windows window , When calculating data, this Double The value of the data will become null; So , Need to be in Filter Data cleaning and filtering , Filter it out ; The correct filtering posture is like this ：

.filter((item)-> {// Abnormal data cleaning 
            if (item==null) return false;
            Double mvalue = item.getMvalue();
            if (mvalue == null || mvalue.equals(Double.NaN)){
               return false;
            }
            return true;
          }
       );