Serializer problem

[mnlipp]

Occurs on a user's very first login only:

Problem invoking handler with LastConsoleLayout#15 [channels=[WebConsole#1{ConsoleConnection#15}↔guiHttp{WebAppMsgChannel#578}↔…]]: No serializer found for class java.lang.Object and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: java.util.ArrayList[2])

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class java.lang.Object and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: java.util.ArrayList[2])
	at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:77)
	at com.fasterxml.jackson.databind.SerializerProvider.reportBadDefinition(SerializerProvider.java:1328)
	at com.fasterxml.jackson.databind.DatabindContext.reportBadDefinition(DatabindContext.java:414)
	at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:53)
	at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:30)
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:119)
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:79)
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:18)
	at com.fasterxml.jackson.databind.SerializerProvider.defaultSerializeValue(SerializerProvider.java:1172)
	at org.jgrapes.webconsole.base.JsonRpc$Serializer.serialize(JsonRpc.java:265)
	at org.jgrapes.webconsole.base.JsonRpc$Serializer.serialize(JsonRpc.java:229)
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:502)
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:341)
	at com.fasterxml.jackson.databind.ObjectMapper._writeValueAndClose(ObjectMapper.java:4811)
	at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:4035)
	at org.jgrapes.webconsole.base.events.ConsoleCommand.emitJson(ConsoleCommand.java:75)
	at org.jgrapes.webconsole.base.events.LastConsoleLayout.emitJson(LastConsoleLayout.java:71)
	at org.jgrapes.webconsole.base.ConsoleWeblet.onConsoleCommand(ConsoleWeblet.java:827)
	at org.jgrapes.core.internal.HandlerReference.invoke(HandlerReference.java:134)
	at org.jgrapes.core.internal.EventProcessor.invokeHandlers(EventProcessor.java:213)
	at org.jgrapes.core.internal.EventProcessor.run(EventProcessor.java:180)
	at java.base/java.util.concurrent.ThreadPerTaskExecutor$TaskRunner.run(Unknown Source)
	at java.base/java.lang.VirtualThread.run(Unknown Source)