DLS: do not swallow exceptions in initialization

Author: smarter

language-server/src/dotty/tools/languageserver/DottyLanguageServer.scala

@@ -5,6 +5,7 @@ import java.net.URI
 import java.io._
 import java.nio.file._
 import java.util.concurrent.CompletableFuture
+import java.util.function.Function
 
 import com.fasterxml.jackson.databind.ObjectMapper
 
@@ -133,6 +134,16 @@ class DottyLanguageServer extends LanguageServer
     // Do most of the initialization asynchronously so that we can return early
     // from this method and thus let the client know our capabilities.
     CompletableFuture.supplyAsync(() => drivers)
+      .exceptionally {
+        // Can't use a function literal here because of #2367
+        new Function[Throwable, Nothing] {
+          def apply(ex: Throwable) = {
+            ex.printStackTrace
+            exit()
+            sys.error("Unreachable")
+          }
+        }
+      }
 
     new InitializeResult(c)
   }