See #2260 (comment) and microsoft/vscode-java-debug#1148 (comment).

We frequently received issues about "java.lang.IllegalArgumentException: URI is not hierarchical" during "Initialize workspace". The root cause is that the user's settings like java.settings.url or java.format.settings.url point to an illegal url format, and JLS just fails silently.

I think we can improve two things:

• Since this error is fatal, we should report a more explicit notification to tell user what's happening and guide user how to fix it.
• We should catch this exception in JLS, and avoid breaking the startup of language server.