fix crash on not passing "userLanguages" option

Since the server can be used by various clients and there is no
guarantee that the "userLanguages" are provided, handle that
case gracefully and don't crash.

src/server.ts

@@ -156,7 +156,9 @@ async function createProjectService(
     editor: {
       connection,
       globalSettings: params.initializationOptions.configuration as Settings,
-      userLanguages: params.initializationOptions.userLanguages,
+      userLanguages: params.initializationOptions.userLanguages
+        ? params.initializationOptions.userLanguages
+        : {},
       // TODO
       capabilities: {
         configuration: true,