TypeError: Cannot read property 'split' of undefined in React js

Hii guys i am trying to building a music player application then i am getting an error like Cannot read properly split undefined don’t know what’s going on wrong please try to fix my error

   import axios from "axios";
  
    export const selectRandomKey = () => {
      const keys = process.env.REACT_APP_YouTube_Keys.split(""); //we are splitting the api keys to make an array
      const random = Math.floor(Math.random() * Math.floor(keys.length)); //this will get a random number
      return keys[random];
    }
    
    export default axios.create({
      baseURL: "https://www.googleapis.com/youtube/v3",
      params: {
        part: "snippet",
        videoCategoryId: "10",
        type: "video",
        key: selectRandomKey()
      }
    });