When I run the CMD 'npm run dev' throw an err on terminal console

[xaviertung]

When I run the CMD 'npm run dev' throw an err on terminal console:

[1] to be executed: "node bin/server.js" [0] ==> Webpack development server listening on port 8080 [1] [webpack-isomorphic-tools] [error].development()method is now deprecated (for server-side instance only, not for webpack plugin instance) and has no effec t. Set up a properprocess.env.NODE_ENVvariable instead.

It always make the 'webpack-hot-middleware' bad. Is this a bug and how to resolve it? This is my question, thx!