JSONLDWriter#endRdf causing NullPointerException when node is missing RDF_FIRST property

[vallerap]

Hello,

we recently switched to rdf4j 4.3.8 and noticed that we´re having issues processing JSON-LD through JSONLDWriter, receiving the following:

java.lang.NullPointerException: Cannot invoke "java.util.List.get(int)" because the return value of "com.github.jsonldjava.core.JsonLdApi$NodeMapNode.get(Object)" is null
	at com.github.jsonldjava.core.JsonLdApi.fromRDF(JsonLdApi.java:2053) ~[jsonld-java-0.13.6.jar:?]
	at com.github.jsonldjava.core.JsonLdApi.fromRDF(JsonLdApi.java:1936) ~[jsonld-java-0.13.6.jar:?]
	at com.github.jsonldjava.core.JsonLdProcessor.fromRDF(JsonLdProcessor.java:469) ~[jsonld-java-0.13.6.jar:?]
	at org.eclipse.rdf4j.rio.jsonld.JSONLDWriter.endRDF(JSONLDWriter.java:135) ~[eclipse-rdf4j-4.3.8-onejar.jar:4.3.8]

I looked at the implementation of the method JsonLdApi#fromRDF and this seems to be caused by the missing property defined by RDF_FIRST (http://www.w3.org/1999/02/22-rdf-syntax-ns#first)

I´ve rebuilt json-ld-java (v. 0.13.6) implmenenting a nullity check in JsonLdApi#fromRDF
(visible in the stacktrace) the issue seems to be fixed, however, I was wondering if there was another way to achieve this result?

[hmottestad]

Could you provide some code for us to reproduce this?