dropdown.js callback is not a function on repeat focus

Bug: dropdown.js — load_tlib() throws “callback is not a function” on repeat focus/hover

Affected asset: https://cdn.gtranslate.net/widgets/latest/dropdown.js (the “dropdown” widget variant; other variants may share the same helper — worth checking float.js / dwf.js / globe.js too).

Root cause

load_tlib(callback) is defined as a general-purpose helper that lazy-injects lib.min.js and then runs a callback once it’s loaded:

function load_tlib(callback){
  if(!window.gt_translate_script){
    window.gt_translate_script = document.createElement('script');
    gt_translate_script.src = 'https://cdn.gtranslate.net/widgets/latest/lib.min.js';
    document.body.appendChild(gt_translate_script);
    if(callback) gt_translate_script.addEventListener('load', callback, {once:true});
  } else {
    callback && callback();
  }
}

But it is also registered directly as a native DOM event listener:

e.addEventListener('pointerenter', load_tlib);
e.addEventListener('focusin', load_tlib);

When the browser invokes an event listener, it always passes the triggering Event object as the argument. So on every focusin/pointerenter fired this way, callback inside load_tlib is actually a native Event, not a function.

• First call (window.gt_translate_script not yet set): goes into the if branch. gt_translate_script.addEventListener('load', callback, {once:true}) is called with callback = an Event object. Per the addEventListener spec this is silently ignored (no crash, but also no real “on load” callback ever gets registered).
• Any subsequent call on the same wrapper (user re-focuses or re-hovers the widget after the first interaction): window.gt_translate_script now exists, so execution hits the else branch: callback && callback();. callback is again a truthy Event object, so this attempts to invoke the Event instance as a function — which throws:

Uncaught TypeError: callback is not a function

Steps to reproduce

1. Load a page with the dropdown widget using default settings (url_structure: 'none', so the interaction-based lazy-load path runs).
2. Move keyboard focus into the widget’s wrapper element once, or hover it with a pointer once — no error; window.gt_translate_script gets set on this first pass.
3. Move focus/hover away and then back onto the wrapper a second time (or trigger focusin/pointerenter on it again in any way) — Uncaught TypeError: callback is not a function is thrown from the callback && callback(); line inside load_tlib.
4. This repeats on every subsequent focus/hover cycle on the same page load.

Suggested fix

load_tlib is used both as a plain callback-style helper (e.g. called manually inside doGTranslate with a real function) and directly as a native event listener — these two calling conventions are incompatible without normalizing the argument. Either:

• (a) Wrap it before attaching as a listener, so it’s never invoked with the native Event as its argument: e.addEventListener('focusin', () => load_tlib());e.addEventListener('pointerenter', () => load_tlib());
• (b) Or guard the type inside load_tlib itself, so any non-function argument is ignored instead of crashing: if (typeof callback === 'function') callback(); (and the same guard before the addEventListener('load', callback, ...) call).

Either change is small, localized to load_tlib, and doesn’t affect the widget’s public config/settings.