NullCheckReference error

[admin3]

I am getting this error which I really feel it's a bug

org.neo4j.cypher.internal.physicalplanning.ast.NullCheckReference

So lets take this from the beginning.
When I run this query everythinks works fine.

match (manufacturer)-[:HAS_BRAND]-(brand:Brand)-[:HAS_VARIANT]->(variants:Variant)
with manufacturer, brand, collect(variants) as variantList

unwind variantList as variant
Unwind range(1,variantList.nCars) as carID
return manufacturer,variant,carID

In my results and when checking the Table I see this:

manufacturer             variant                      carID
{name:"VW",.. }         {name:"Golf", nCars:12}       1
{name:"VW",.. }         {name:"Golf", nCars:12}       2
{name:"VW",.. }         {name:"Golf", nCars:12}       3
.....
{name:"VW",.. }         {name:"Golf", nCars:12}       12
{name:"VW",.. }         {name:"Tiguan", nCars:3}      1
{name:"VW",.. }         {name:"Tiguan", nCars:3}      2
.............

So you can see the table looks alright.
But when I change my query to this.

match (manufacturer)-[:HAS_BRAND]-(brand:Brand)-[:HAS_VARIANT]->(variants:Variant)
with manufacturer, brand, collect(variants) as variantList

unwind variantList as variant
Unwind range(1,variantList.nCars) as carID
create (:Car {name: manufacturer.name + ' - ' + variant.name + ' - Car ' + carID})

.. I get the above error org.neo4j.cypher.internal.physicalplanning.ast.NullCheckReference.

I notice that if I change the last line to create (:Car {name: manufacturer.name + ' - Car ' + carID}) everything works i.e. I removed the variant.name.

Anyway this doesn't make sense and also I want to have that name.

Please help

[admin3]

I found a way to do this but still doesn't explain the previous error.

Anyway my fix is

match (manufacturer)-[:HAS_BRAND]-(brand:Brand)-[:HAS_VARIANT]->(variants:Variant)
Unwind range(1,variants.nCars) as carID
create (:Car {name: manufacturer.name + ' - ' + variants.name + ' - Car ' + carID})

[dana_canzano]

what version of Neo4j?
When you run he query which results in failure is there a stacktrace logged in the logs\debug.log?

[admin3]

I used version 4.0.3.

Sorry I have moved on and can't check the log file now.
Is it saved from yesterday?
Thanks

[dana_canzano]

the log should be saved unless it got auto rotated off however I believe the default is to keep 7 days worth
But also we encountered a similar org.neo4j.cypher.internal.physicalplanning.ast.NullCheckReference and have addressed this in the next release of 4.0.x and thus this will be addressed in 4.0.4 (not yet released). However whether of not it is the exact same root cause as yours is not yet known given the absence of a complete logged stack trace. It may be one in the same? may be ?? or