Everything works, but I’m getting a console error

This is the Script:

This is the page: https://intro-component-sign-up-five.vercel.app/

  const spanContainer = document.querySelectorAll(".form-container span");
  const spanImg = document.querySelectorAll(".errorIcon")
  const submitBtn = document.querySelector(".submit");
  const inputAll = document.querySelectorAll("form input");
  const input = document.querySelector("input");
  let formData = {}; // objeto para armazenar os dados do formulário

  input.addEventListener("input", function(event) {
    formData[input.name] = input.value; // atualiza o valor do objeto com o valor atual do input
  });

  //input.addEventListener("input", errorForm);


  function handleClick(event) {
    inputAll.forEach((input) => {
      if(input.value === "") {
        event.preventDefault();
        errorForm();  
      }
    }) 
  }

  function errorForm() {
    
    spanContainer.forEach((span) => {
      if(span.innerText === ""){
        span.classList.add("errorMessage"); 
      } 
      if(span.classList.contains("errorMessage")) {
        span.classList.add("error");
      }
      spanImg.forEach((img) => {
      if(img.classList.contains("errorIcon")) {
        img.classList.add("selected");
      }
      })
    inputAll.forEach((input) => {
      if(input.classList.contains("submit") === false && input.value === "") {
        input.classList.add("error");
        input.nextElementSibling.nextElementSibling.classList.add("error");
      } else {
        input.classList.remove("error");
        input.nextElementSibling.classList.remove("errorMessage");
        input.nextElementSibling.classList.remove("selected");
        input.nextElementSibling.nextElementSibling.classList.remove("error");

      }
    })  
    })
  }


  submitBtn.addEventListener("click", handleClick);

Things work fine, just the way I want it to work, but I keep getting this console error:

Uncaught TypeError: Cannot read properties of null (reading 'classList')
at script.js:41:51
at NodeList.forEach (<anonymous>)
at script.js:35:12
at NodeList.forEach (<anonymous>)
at errorForm (script.js:23:17)
at script.js:16:7
at NodeList.forEach (<anonymous>)
at HTMLInputElement.handleClick (script.js:13:12)

I tried to fix it by removing the second “nextElementSibling”, but when I do it the page doesn’t work the way I want anymore. The errorMessage is not removed once I submit again after I fulfill the respective input.