Unbreak HMR listener

Reviewed By: sam-swarr

Differential Revision: D3042801

fb-gh-sync-id: 2f06f2efbdf3d04ce4db0cf847ebe76d05fb109f
shipit-source-id: 2f06f2efbdf3d04ce4db0cf847ebe76d05fb109f

local-cli/server/util/attachHMRServer.js

@@ -292,7 +292,7 @@ function attachHMRServer({httpServer, path, packagerServer}) {
             () => {
               // do nothing, file was removed
             },
-          ).finally(() => {
+          ).then(() => {
             client.ws.send(JSON.stringify({type: 'update-done'}));
           });
         });