getInput = (popup, inputClass) => {
  if (!inputClass) {
    return null
  }
  switch (inputClass) {
    case 'select':
    case 'textarea':
    case 'file':
      return popup.querySelector(`.${swalClasses.popup} > .${swalClasses[inputClass]}`)
    case 'checkbox':
      return popup.querySelector(`.${swalClasses.popup} > .${swalClasses.checkbox} input`)
    case 'radio':
      return (
        popup.querySelector(`.${swalClasses.popup} > .${swalClasses.radio} input:checked`) ||
        popup.querySelector(`.${swalClasses.popup} > .${swalClasses.radio} input:first-child`)
      )
    case 'range':
      return popup.querySelector(`.${swalClasses.popup} > .${swalClasses.range} input`)
    default:
      return popup.querySelector(`.${swalClasses.popup} > .${swalClasses.input}`)
  }
}
@param {HTMLElement} popup
@param {import('./renderers/renderInput').InputClass | SweetAlertInput} inputClass
@returns {HTMLInputElement | null}