error on export database

[lvca]

Discussed in #485

^{Originally posted by kran August 11, 2022}
export database file://a.jsonl.tgz,

JsonGraphSerializer.java

object.put("r", document.getIdentity().toString());

identity is null in some situations?

Caused by: com.arcadedb.integration.exporter.ExportException: Error on writing to 'exports/a.jsonl.tgz'
	at com.arcadedb.integration.exporter.Exporter.exportDatabase(Exporter.java:86)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at com.arcadedb.query.sql.parser.ExportDatabaseStatement.executeSimple(ExportDatabaseStatement.java:74)
	... 72 common frames omitted
Caused by: java.lang.NullPointerException: null
	at com.arcadedb.serializer.JsonGraphSerializer.serializeGraphElement(JsonGraphSerializer.java:55)
	at com.arcadedb.serializer.JsonGraphSerializer.serializeGraphElement(JsonGraphSerializer.java:67)
	at com.arcadedb.serializer.JsonGraphSerializer.serializeGraphElement(JsonGraphSerializer.java:38)
	at com.arcadedb.integration.exporter.format.JsonlExporterFormat.exportDocuments(JsonlExporterFormat.java:141)
	at com.arcadedb.integration.exporter.format.JsonlExporterFormat.exportDatabase(JsonlExporterFormat.java:111)
	at com.arcadedb.integration.exporter.Exporter.exportDatabase(Exporter.java:73)
	... 77 common frames omitted

after the exception, database is closed, i have to restart application.