"LtThreadPoolExecutorMonitor" java.lang.IllegalArgumentException: Label cannot be null

[hopp19]

Starting LanguageTool server on the command-line, occasionally I see the following error message:

$ java -cp /opt/LanguageTool-6.5/languagetool-server.jar org.languagetool.server.HTTPServer --port 8081 --allow-origin
2024-11-19 23:28:00.169 GMT+01:00 INFO  org.languagetool.server.DatabaseAccessOpenSource Not setting up database access, dbDriver is not configured
2024-11-19 22:28:00 +0000 Setting up thread pool with 10 threads
Exception in thread "LtThreadPoolExecutorMonitor" java.lang.IllegalArgumentException: Label cannot be null.
	at io.prometheus.client.SimpleCollector.labels(SimpleCollector.java:69)
	at org.languagetool.tools.LtThreadPoolExecutor$1.run(LtThreadPoolExecutor.java:60)
	at java.base/java.util.TimerThread.mainLoop(Timer.java:556)
	at java.base/java.util.TimerThread.run(Timer.java:506)
2024-11-19 23:28:02.962 GMT+01:00 WARN  org.languagetool.language.identifier.DefaultLanguageIdentifier fastText not configured - language detection performance will be degraded. See https://dev.languagetool.org/http-server#starting-from-command-line for instructions.
2024-11-19 23:28:02.980 GMT+01:00 INFO  org.languagetool.server.TextChecker A/B-Test enabled: []
2024-11-19 22:28:03 +0000 Starting LanguageTool 6.5 (build date: 2024-09-27 11:27:57 +0200, 5c6be17) server on http://localhost:8081...
2024-11-19 22:28:03 +0000 Server started

The server seems to be running fine, though.

This is on a fresh Ubuntu 24.04.1 installation using OpenJDK 11:

$ java --version
openjdk 11.0.25 2024-10-15
OpenJDK Runtime Environment (build 11.0.25+9-post-Ubuntu-1ubuntu124.04)
OpenJDK 64-Bit Server VM (build 11.0.25+9-post-Ubuntu-1ubuntu124.04, mixed mode, sharing)

Aside from reporting this bug, I'd like to ask does the exception actually degrade LanguageTool operation in any way or is this mostly cosmetic?