"Script error" on IndexedDB with window.onerror()

Question

I develop a nw.js app. I try to save javascript errors to indexedDB (via Dexie.js) but I only see "Script error" instead of full details I get with window.onerror() function.

Here is related part of my code:

window.onerror = (message, source, lineno, colno, error) => {
    spawn(function* () {
      db.errors.add({
        source: source,
        message: message,
        lineno: lineno,
        colno: colno,
        error: error,
      });
    });
  };