[BUG] Null relationship nodes in writes

[ccloes]

Describe the bug
When a relationship node is null there should be a check prior to trying to write to the database. It results in failed writes and DB log messages like the following:

2023-08-22 20:59:07.738+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'targetRevision': (:ArgoApp {targetRevision: null})
2023-08-22 21:12:26.632+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'targetRevision': (:ArgoApp {targetRevision: null})
2023-09-27 19:35:41.892+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})
2023-09-27 20:02:18.203+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})
2023-09-27 20:57:00.068+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})
2023-09-27 21:31:52.992+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})
2023-09-27 21:50:15.457+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})
2023-09-27 22:29:00.706+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})
2023-09-27 23:00:39.617+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})
2023-09-28 06:30:22.295+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})
2023-09-28 07:46:50.282+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})
2023-09-28 12:47:10.717+0000 WARN  1 times: org.neo4j.graphdb.QueryExecutionException: Cannot merge the following node because of null property value for 'name': (:GitBranch {name: null})

To Reproduce
Steps to reproduce the behavior:

1. Create a relationship node of null property field
2. Write it to the database, and the DB will log errors like above
3. Cry

Expected behavior
Nodestream should check for this prior to sending it to the database to prevent wasted cycles and errors in the logs. Nodestream should also log warnings of null relationship nodes.