Listen for uncaught errors using window.addEventListener('error', ...)

window.onerror.js

<script>
    window.addEventListener('error', (event) => {
        const { message, filename, lineno, colno, error } = event;
        console.log('Captured uncaught error:', message, filename, lineno, colno, error.stack);
    });

    setTimeout(() => {
        try {
            throw new Error('An unexpected error occurred (2)');
        } catch (ex) {
            // Ignore
        }
    });

    throw new Error('An unexpected error occurred (1)');
</script>