Missing class properties transform

Hello guys, i am learning webdevelopment and React, right now i am strugling with implementing the React Map into the fullstack framework that i am workink with, it's a derivation of Meteor, called VulcanJs.org and i am having trouble with the syntax of the code.

I am keep geting Missing class properties transform using the code youy provide, reading on internet they say is a webpack config problem, but i have no ideea how to solve it.

So i wanted to ask what is the "normal" way of writing the code for youre React Map ?