Flink sql with LAG function NullPointerException

Question

I want to make a query with the LAG function. And get Job Exception without any explanations.

Code:

private static void t1_LeadLag(DataStream<UserModel> ds, StreamExecutionEnvironment env) {
    StreamTableEnvironment te = StreamTableEnvironment.create(env);
    Table t = te.fromDataStream(ds, Schema.newBuilder().columnByExpression("proctime", "proctime()").build());

    te.createTemporaryView("users", t);

    Table res = te.sqlQuery("SELECT userId, `count`,\n" +
            " LAG(`count`) OVER (PARTITION BY userId ORDER BY proctime) AS prev_quantity\n" +
            " FROM users");

    te.toChangelogStream(res).print();
}

Input:

{"userId":3,"count":0,"dt":"2023-04-28T07:44:21.551Z"}

Exception: I remove part about basic JobExecutionException and kept the important(i think)

Caused by: java.lang.NullPointerException
    at org.apache.flink.table.data.GenericRowData.getInt(GenericRowData.java:149)
    at org.apache.flink.table.data.RowData.lambda$createFieldGetter$245ca7d1$6(RowData.java:245)
    at org$apache$flink$table$runtime$functions$aggregate$LagAggFunction$LagAcc$2$Converter.toExternal(Unknown Source)
    at org.apache.flink.table.data.conversion.StructuredObjectConverter.toExternal(StructuredObjectConverter.java:101)
    at UnboundedOverAggregateHelper$15.setAccumulators(Unknown Source)
    at org.apache.flink.table.runtime.operators.over.ProcTimeUnboundedPrecedingFunction.processElement(ProcTimeUnboundedPrecedingFunction.java:92)
    at org.apache.flink.table.runtime.operators.over.ProcTimeUnboundedPrecedingFunction.processElement(ProcTimeUnboundedPrecedingFunction.java:42)
    at org.apache.flink.streaming.api.operators.KeyedProcessOperator.processElement(KeyedProcessOperator.java:83)
    at org.apache.flink.streaming.runtime.io.RecordProcessorUtils.lambda$getRecordProcessor$0(RecordProcessorUtils.java:60)
    at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask$StreamTaskNetworkOutput.emitRecord(OneInputStreamTask.java:237)
    at org.apache.flink.streaming.runtime.io.AbstractStreamTaskNetworkInput.processElement(AbstractStreamTaskNetworkInput.java:146)
    at org.apache.flink.streaming.runtime.io.AbstractStreamTaskNetworkInput.emitNext(AbstractStreamTaskNetworkInput.java:110)
    at org.apache.flink.streaming.runtime.io.StreamOneInputProcessor.processInput(StreamOneInputProcessor.java:65)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.processInput(StreamTask.java:550)
    at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.runMailboxLoop(MailboxProcessor.java:231)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.runMailboxLoop(StreamTask.java:839)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:788)
    at org.apache.flink.runtime.taskmanager.Task.runWithSystemExitMonitoring(Task.java:952)
    at org.apache.flink.runtime.taskmanager.Task.restoreAndInvoke(Task.java:931)
    at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:745)
    at org.apache.flink.runtime.taskmanager.Task.run(Task.java:562)
    at java.base/java.lang.Thread.run(Thread.java:829)