When I try to output a property to the console inside a method, I get error error1 is not defined for error1 and console message "undefined" for error2. What am I doing wrong?

class myClass {
  constructor(setting) {
    let error1 = ["fdf", "gff"];
    this.error2 = ["fdf", "gff"];

    for (let i = 0; i < formFields.length; i++) {
        if (formFields[i].tagName === "BUTTON") {
        continue;
    }
      formFields[i].addEventListener("change", this.method.bind(this);
    } 
   }
   isValid(el){
   ...
  }
  method(){
    isValid(this)
    console.log(error1); 
    console.log(this.error2);
  }

Here's a complete example on codsandbox. https://codesandbox.io/s/sleepy-moon-m9kr6?file=/src/index.js