Fix semantic highlighting

Author: fhammerschmidt

server/src/server.ts

@@ -1135,7 +1135,7 @@ function onMessage(msg: p.Message) {
               ],
               tokenModifiers: [],
             },
-            documentSelector: null,
+            documentSelector: [{ scheme: "file", language: "rescript" }],
             // TODO: Support range for full, and add delta support
             full: true,
           },