[macOS][Firefox] If another Chromium browser is set as default in the OS and a page is launched in Safari, both browsers will launch

[acornestean]

Description:
If Safari is not the default browser as another Chromium browser is set as the default one, launching a page in Safari will launch the page in the default browser as well, at the same time.

Steps to reproduce:

1. Set another Chromium browser as default in the macOS system preferences
2. Load the Firefox Firefox Bridge v0.1 in Firefox
3. On the welcome page, select Safari as the other browser to send pages into
4. Access https://www.wikipedia.org/ and click the toolbar button
5. Notice that both the default set browser and Safari will launch and both will load the page from Step (4)

NOTE 1: The issue only occurs on the first launch of the browsers to which pages are being sent. On subsequent page launching, only Safari will receive the launched pages.
NOTE 2: The issue does not occur when other browsers are selected in the welcome page

Expected:
Only the selected browser (Safari) should get launched and load the page sent from Firefox.

Actual:
Both Safari (the selected browser) and the OS default browser get launched when sending a page from Firefox .

[GregSherman]

I've tried to reproduce, but I'm unable to. Do you have more information? OS version, which chromium browsers, firefox version, etc

[acornestean]

@GregSherman

I used the latest Nightly 125.0a1 (03.05.2024) and Chrome v.122.0.6261.57 / Brave v.1.63.165 (Chromium 122.0.6261.94) and Safari v.14.1 (16611.1.21.161.6) on macOS 11.3.1.
I attached two screen recordings of the issue occurring. Hope this helps !

Google Chrome set as default browser in the OS and Safari selected on the welcome page:

Screen.Recording.2024-03-06.at.12.53.10.1.mov

Brave set as default browser in the OS and Safari selected on the welcome page

Screen.Recording.2024-03-06.at.12.56.24.1.mov