Is Who Unfollowed Me? safe?

let enterButton = document.getElementById("enter"),
  licenseDiv = document.getElementById("license-info"),
  emailInput = document.getElementById("email");
emailInput.setAttribute("placeholder", chrome.i18n.getMessage("licensePlaceholder")), document.querySelectorAll("[data-locale]").forEach(a => {
  a.innerHTML = chrome.i18n.getMessage(a.dataset.locale)
});

function activeLicenseHtml(a) {
  return chrome.i18n.getMessage("licenseActive") + ": " + a.email + "<br>" + chrome.i18n.getMessage("licenseExpiration") + ": " + a.expiration
}
chrome.storage.local.get(["license"]).then(a => {
  a.license !== void 0 && (licenseDiv.innerHTML = activeLicenseHtml(a.license))
}), enterButton.addEventListener("click", function() {
  let a = emailInput.value;
  return a ? void fetch("https://www.invertexto.com/licenses/check.php?product=unfollowed&email=" + a).then(a => a.json()).then(b => {
    if ("ok" != b.status) return alert(b.status);
    const c = {
      email: a,
      expiration: b.expiration
    };
    chrome.storage.local.set({
      license: c
    }, () => {
      licenseDiv.innerHTML = activeLicenseHtml(c)
    })
  }).catch(() => {
    alert(chrome.i18n.getMessage("unexpectedError"))
  }) : alert(chrome.i18n.getMessage("licenseEnterAlert"))
});