KeyNotFound Error in join

[MarkMpn]

https://markcarrington.dev/2021/04/29/sql-4-cds-v5-released/#comment-10201

select DISTINCT
(select D.displayname
from metadata.entity as D
where D.logicalname=R.referencingentity) as ThisEntity,
(select D.logicalname
from metadata.entity as D
where D.logicalname=R.referencingentity) as [ThisEntity Logical Name],
R.introducedversion as Version,
E.displayname as DependsOn,
E.logicalname as [DependsOn Logical Name],
E.description as [DependsOn Description]
from metadata.relationship_n_1 as R
left join metadata.entity as E
on E.schemaname=R.referencedentity
where

R.referencingentity='opportunity'