close the driver on crash

bin/main.ml

@@ -6,7 +6,12 @@ open Twitter
 let start driver =
   let name_driver = prepare driver in
   let data_driver = run_process name_driver [] in
-  let session_id = get_session () in
+  let session_id =
+    try get_session () with
+    | Any msg ->
+      stop_process data_driver;
+      raise (Any ("Can't get the session ID: " ^ msg))
+  in
   data_driver, session_id
 ;;