Demote user errors

Summary:
One is keytar, which just needed a context.

The second one is happening every time someone uses Flipper
and not being on Lighthouse, spamming our log category besides
actually being properly handled.

Reviewed By: nikoant

Differential Revision: D28479791

fbshipit-source-id: 029721df46d12b2942b590a232618ef039a2323d

desktop/app/src/dispatcher/user.tsx

@@ -29,7 +29,7 @@ export default (store: Store, _logger: Logger) => {
     })
     .catch((e) => {
       store.dispatch(logout());
-      console.error(e);
+      console.warn('Failed to load user:', e);
     });
 
   let prevUserName = store.getState().user.name;