Normally websites cannot close the current tab or window using a script command unless they opened the tab or window using a script command. It's possible that the application works that way; I have no idea. Can you check with the vendor on whether they are aware of a problem?

Meanwhile, perhaps we can come up with a workaround. Is the problem that the last window closes completely, resulting in Firefox shutting down? You can change a setting so that Firefox stays open with a blank tab, and then you should be able to use the History menu to re-open the tab that closed. Or if the tab was in a different window, you can use the History menu to re-open that closed window. Here's the setting:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste tabs and pause while the list is filtered

(3) Double-click the browser.tabs.closeWindowWithLastTab preference to switch the value from true to false

After this change, you may need to use the Exit command to close Firefox. That would be either:

• "3-bar" menu button > power symbol on the bottom row of the menu
• (menu bar) File > Exit

Does that help at all?

Your post is somewhat similar to a problem posted by another user:

when I click the link [on efsllc.com and factorfox.com] to create the .xls report, the current tab is closed and replaced by a blank new tab while the .xls file is downloaded and appears in my download folder.

So to summarize, current tab is closed when link is clicked, .xls doc goes to download folder and a blank new tab is created.

https://support.mozilla.org/questions/1164456#answer-979321

That one is not yet solved.