Neo4j 2.2 NullPointerException when using indexed property with null value - neo4j

Question

We are running Neo4j on Windows Server 2008 R2 with JRE 1.7.0_79.
When executing certain queries which hit an index, we are getting a NullPointerException.
The query looks like the one below:
MATCH (assignee)<-[:ASSIGNED_TO]-(task:Task)-[instanceOfRel:INSTANCE_OF]->(distribution:Distribution)
WITH assignee, task, distribution, instanceOfRel.CountryUid AS applicableCountryUid
OPTIONAL MATCH (country:Country)
WHERE country.Uid = applicableCountryUid
RETURN assignee, task, distribution, country
And the query fails on the WHERE clause if applicableCountryUid is null.
If the index is removed from the schema, the query will work fine.
A partial extract of the full exception stack is:
"Received an unexpected HTTP status when executing the request.The response status was: 400 Bad RequestThe response from Neo4j (which might include useful detail!) was: {
"exception" : "NullPointerException", "fullname" : "java.lang.NullPointerException",
"stackTrace" : [ "org.neo4j.kernel.api.impl.index.LuceneDocumentStructure$ValueEncoding$2.canEncode(LuceneDocumentStructure.java:90)",
"org.neo4j.kernel.api.impl.index.LuceneDocumentStructure.newQuery(LuceneDocumentStructure.java:219)",
"org.neo4j.kernel.api.impl.index.LuceneIndexAccessorReader.lookup(LuceneIndexAccessorReader.java:96)",
"org.neo4j.kernel.impl.api.store.DiskLayer.nodesGetFromIndexLookup(DiskLayer.java:601)",
"org.neo4j.kernel.impl.api.store.CacheLayer.nodesGetFromIndexLookup(CacheLayer.java:349)",
"org.neo4j.kernel.impl.api.StateHandlingStatementOperations.nodesGetFromIndexLookup(StateHandlingStatementOperations.java:591)",
"org.neo4j.kernel.impl.api.ConstraintEnforcingEntityOperations.nodesGetFromIndexLookup(ConstraintEnforcingEntityOperations.java:210)",
This doesn't seem to affect the queries in earlier 2.1.x versions of Neo4j, but we are only seeing this issue with 2.2.0 and 2.2.2.
Is there a known issue or workarounds for working with the indices without rewriting queries?

Answer 1

Are the results meaningful when applicableCountryUid is null? The WHERE clause doesn't make much sense then.
Maybe you can filter out the null cases:
MATCH (assignee)<-[:ASSIGNED_TO]-(task:Task)-[instanceOfRel:INSTANCE_OF]->(distribution:Distribution)
WHERE has(instanceOfRel.CountryUid)
WITH assignee, task, distribution, instanceOfRel.CountryUid AS applicableCountryUid
OPTIONAL MATCH (country:Country)
WHERE country.Uid = applicableCountryUid
RETURN assignee, task, distribution, country