Weij33t

cols: prevState.cols,

this.setState((prevState) => {
  return {
    cols: prevState.map((col, index) => {
      if (index !== id) {
        return col;
      }

      return {
        ...col,
        cards: [
           ...col.cards,
           {/*new card fields*/}
        ]
      }
    }
  }
})

target: process.env.NODE_ENV === "development" ? "web" : "browserslist",

"start": "cross-env NODE_ENV=development webpack serve"