Issue with popstate event on Safari Version 12.0 (13606.2.11)

Hi,

I'm having a problem using window.onpopstate event. i'm using it to handle the back from browser, but under some circustances the event fires without being triggered by any button, just after being initialized.

Let me be more clear:
Page 1: Contains the onpopstate event handler
Page 2: Page after the page 1.

When i come from page 2 to page 1, after being initialized, the popstate event is triggered without any other button click.

Is this a bug from Safari? (Happens only on Safari)