"Client triggered an unexpected error" when loading empty CSV file

[also]

Running LOAD CSV WITH HEADERS with an empty CSV file causes an unexpected, unrecoverable error.

Neo4j Version: 3.1.3
Operating System: macOS 10.12.3
API: Cypher

Steps to reproduce

Run this in cypher-shell:

// assert correct line count
LOAD CSV WITH HEADERS FROM "file:///path/to/empty.csv" AS line
RETURN count(*);

empty.csv is an empty (0 byte) file.

Expected behavior

An error like "Invalid CSV" is returned. The error is recoverable in the client session, and the server does not log an exception.

Actual behavior

The cypher-shell session shows this error, and is no longer usable:

next on empty iterator
Exception in thread "Thread-0" org.neo4j.driver.v1.exceptions.ClientException: Cannot run more statements in the current session as an unrecoverable error has happened. Please close the current session and re-run your statement in a new session.
        at org.neo4j.driver.internal.NetworkSession.ensureNoUnrecoverableError(NetworkSession.java:274)
        at org.neo4j.driver.internal.NetworkSession.reset(NetworkSession.java:132)
        at org.neo4j.shell.state.BoltStateHandler.reset(BoltStateHandler.java:169)
        at org.neo4j.shell.CypherShell.reset(CypherShell.java:183)
        at org.neo4j.shell.CypherShell$1.run(CypherShell.java:190)

This is logged in the server's debug.log:

2017-04-01 18:28:17.784+0000 ERROR [o.n.b.v.r.ErrorReporter] Client triggered an unexpected error [UnknownError]: next on empty iterator. See debug.log for more details, reference a937cd46-55dd-44c6-b91a-ab0745c8cb90.
2017-04-01 18:28:17.784+0000 ERROR [o.n.b.v.r.ErrorReporter] Client triggered an unexpected error [UnknownError]: next on empty iterator, reference a937cd46-55dd-44c6-b91a-ab0745c8cb90. next on empty iterator
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 org.neo4j.cypher.internal.compiler.v3_1.spi.CSVResources$$anon$1.next(CSVResources.scala:101)
	at org.neo4j.cypher.internal.compiler.v3_1.spi.CSVResources$$anon$1.next(CSVResources.scala:79)
	at org.neo4j.cypher.internal.compiler.v3_1.pipes.LoadCSVPipe$$anonfun$internalCreateResults$1.apply(LoadCSVPipe.scala:111)
	at org.neo4j.cypher.internal.compiler.v3_1.pipes.LoadCSVPipe$$anonfun$internalCreateResults$1.apply(LoadCSVPipe.scala:103)
	at scala.collection.Iterator$$anon$12.nextCur(Iterator.scala:434)
	at scala.collection.Iterator$$anon$12.hasNext(Iterator.scala:440)
	at scala.collection.Iterator$class.foreach(Iterator.scala:893)
	at scala.collection.AbstractIterator.foreach(Iterator.scala:1336)
	at org.neo4j.cypher.internal.compiler.v3_1.pipes.EagerAggregationPipe.internalCreateResults(EagerAggregationPipe.scala:101)
	at org.neo4j.cypher.internal.compiler.v3_1.pipes.PipeWithSource.createResults(Pipe.scala:131)
	at org.neo4j.cypher.internal.compiler.v3_1.pipes.PipeWithSource.createResults(Pipe.scala:128)
	at org.neo4j.cypher.internal.compiler.v3_1.executionplan.DefaultExecutionResultBuilderFactory$ExecutionWorkflowBuilder.createResults(DefaultExecutionResultBuilderFactory.scala:98)
	at org.neo4j.cypher.internal.compiler.v3_1.executionplan.DefaultExecutionResultBuilderFactory$ExecutionWorkflowBuilder.build(DefaultExecutionResultBuilderFactory.scala:68)
	at org.neo4j.cypher.internal.compiler.v3_1.executionplan.InterpretedExecutionPlanBuilder$$anonfun$getExecutionPlanFunction$1.apply(ExecutionPlanBuilder.scala:164)
	at org.neo4j.cypher.internal.compiler.v3_1.executionplan.InterpretedExecutionPlanBuilder$$anonfun$getExecutionPlanFunction$1.apply(ExecutionPlanBuilder.scala:148)
	at org.neo4j.cypher.internal.compiler.v3_1.executionplan.InterpretedExecutionPlanBuilder$$anon$1.run(ExecutionPlanBuilder.scala:123)
	at org.neo4j.cypher.internal.compatibility.CompatibilityFor3_1$ExecutionPlanWrapper$$anonfun$run$1.apply(CompatibilityFor3_1.scala:277)
	at org.neo4j.cypher.internal.compatibility.CompatibilityFor3_1$ExecutionPlanWrapper$$anonfun$run$1.apply(CompatibilityFor3_1.scala:275)
	at org.neo4j.cypher.internal.compatibility.exceptionHandlerFor3_1$runSafely$.apply(CompatibilityFor3_1.scala:192)
	at org.neo4j.cypher.internal.compatibility.CompatibilityFor3_1$ExecutionPlanWrapper.run(CompatibilityFor3_1.scala:275)
	at org.neo4j.cypher.internal.PreparedPlanExecution.execute(PreparedPlanExecution.scala:26)
	at org.neo4j.cypher.internal.ExecutionEngine.execute(ExecutionEngine.scala:107)
	at org.neo4j.cypher.internal.javacompat.ExecutionEngine.executeQuery(ExecutionEngine.java:59)
	at org.neo4j.bolt.v1.runtime.TransactionStateMachineSPI$1.start(TransactionStateMachineSPI.java:135)
	at org.neo4j.bolt.v1.runtime.TransactionStateMachine$State$1.run(TransactionStateMachine.java:187)
	at org.neo4j.bolt.v1.runtime.TransactionStateMachine.run(TransactionStateMachine.java:77)
	at org.neo4j.bolt.v1.runtime.BoltStateMachine$State$2.run(BoltStateMachine.java:396)
	at org.neo4j.bolt.v1.runtime.BoltStateMachine.run(BoltStateMachine.java:196)
	at org.neo4j.bolt.v1.messaging.BoltMessageRouter.lambda$onRun$3(BoltMessageRouter.java:80)
	at org.neo4j.bolt.v1.runtime.concurrent.RunnableBoltWorker.execute(RunnableBoltWorker.java:135)
	at org.neo4j.bolt.v1.runtime.concurrent.RunnableBoltWorker.run(RunnableBoltWorker.java:89)
	at java.lang.Thread.run(Thread.java:745)

[spacecowboy]

Thanks for the report @also

This is indeed a bug.

[systay]

Fixed here: #9183