"where is not null" causes segmentation fault

"where is not null" statement in this query causes postgres to crash with the following error: "server process (PID 327) was terminated by signal 11: Segmentation fault"

```
SELECT * FROM cypher('access_control_graph', $$
MATCH direct_group= (u:Operator {name: 'Admin'})-[:BELONGS_TO*]->(nop:Group {_type: 'NOP'})-[:PARENT_OF*]->(g2:Group)
OPTIONAL MATCH plants=(nop)-[:RESPONSIBLE_FOR*]->(inp:Group {_type: 'PLANT'}) // subgroups
OPTIONAL MATCH direct_assets=(nop)-[:HAS_PERMISSION*]->(r:Resource {_type: 'ASSET'})
OPTIONAL MATCH indirect_assets=(inp)-[:HAS_PERMISSION*]->(r1:Resource {_type: 'ASSET'})
where inp IS NOT NULL

RETURN direct_group,
plants
,direct_assets
// ,indirect_assets
$$) AS (direct_group agtype,
plants agtype
,direct_assets agtype
--,indirect_assets agtype
);
```