When used with react v16.4, it throws an error in dev console which was introduced after v16.3 in support of removing the componentWillMount, componentWillReceiveProps, and componentWillUpdate lifecycle methods.

Since themr.js uses the componentWillRecieveProps lifecycle method, when used in a project with react v16.4, it throws a console warning. Moreover, this method will be deprecated in future releases of React ( v17.0 )
More about this here.