Unexpected UnknownError in SlotConfiguration

[DominicWuest]

When running the following query:

MATCH ()-[x]-()--()--()--() WHERE false
UNWIND 0 AS n0
MATCH ()--()--(:n1)
MATCH ({n1:x.n2, n1:0})--(), ()--()
RETURN 0 AS n3
	UNION
MERGE ()-[:n4]->()<-[:n5]-()-[:n6]->()-[:n7]->()<-[:n8]-()<-[:n10]-()<-[:n11]-()-[:n12]->()<-[:n13]-()
RETURN 0 AS n3

I encountered the following error:

UnknownError: SlotWithKeyAndAliases(DuplicatedSlotKey(RuntimeKey(x,PropertyKeyName(n2),RELATIONSHIP_TYPE),11),RefSlot(11,false,Any),Set()) (of class org.neo4j.cypher.internal.physicalplanning.SlotConfiguration$SlotWithKeyAndAliases)

I believe the query mentioned above is semantically and syntactically correct and thus no error should be thrown here.

Additionally, this error only occurs after the commit cc5c444, before which the query runs fine.

I encountered this issue when testing queries against the Neo4j 5.18.0 community & enterprise version in a Docker container running alpine v.3.

Steps to reproduce

Run the following query and observe it throws an error:

MATCH ()-[x]-()--()--()--() WHERE false
UNWIND 0 AS n0
MATCH ()--()--(:n1)
MATCH ({n1:x.n2, n1:0})--(), ()--()
RETURN 0 AS n3
	UNION
MERGE ()-[:n4]->()<-[:n5]-()-[:n6]->()-[:n7]->()<-[:n8]-()<-[:n10]-()<-[:n11]-()-[:n12]->()<-[:n13]-()
RETURN 0 AS n3

Expected behavior

The query should run successfully

Actual behavior

The query fails with the error message UnknownError: [...] (of class org.neo4j.cypher.internal.physicalplanning.SlotConfiguration$SlotWithKeyAndAliases)