"org.eclipse.lsp4j.jsonrpc.ResponseErrorException: Internal error." On Scala metals 1.6.3

Error while consuming 'textDocument/documentHighlight' with language server 'Scala Language Server (Metals)'

org.eclipse.lsp4j.jsonrpc.ResponseErrorException: Internal error.
at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.handleResponse(RemoteEndpoint.java:209)
at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.consume(RemoteEndpoint.java:193)
at com.redhat.devtools.lsp4ij.LanguageServerWrapper.lambda$start$4(LanguageServerWrapper.java:385)
at java.base/java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1804)
at java.base/java.util.concurrent.CompletableFuture$AsyncRun.exec(CompletableFuture.java:1796)
at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:507)
at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1491)
at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:2073)
at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:2035)
at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:187)

Unfortunately this is the only error message available to me.

It appears that RedHat telemetry was ignored here (the following interface shouldn't appear)

I would suggest first improving the error logging and telemetry, so the next diagnostic & fix can be easier (in best case it can be 100% delegated to AI)

Start with the textDocument/documentHighlight request and the LanguageServerWrapper.java stack-trace entry, then reproduce the failure using Scala Metals 1.6.3. Investigate why only a generic internal-error response is exposed and why the Red Hat telemetry interface is not shown; done means the diagnostic output and telemetry provide actionable information for this failure.