[FB7841818] Safari and Safari TP crash about one minute after using Xcode to run a Safari App Extension target in them, with 100% reproducibility.

ENVIRONMENT
– macOS 10.15.5
– Xcode Version 11.5 (11E608c)
– Affects both:
1) Safari Version 13.1.1 (15609.2.9.1.2)
2) Safari Technology Preview Release 109 (Safari 14.0, WebKit 15610.1.17.2)

Merely running a Safari App Extension (not a Web Extension) on either Safari or Safari TP leads to the chosen browser crashing after one minute of runtime (see 1:20 of the video attached in Feedback Assistant, "safari_dies_after_a_minute.mp4"). This is true even if the whole content script is commented out. It is also true even if Safari doesn't visit a page at all (stays with just the "new tab" screen) open. So I would guess that it's related to the Xcode-managed debug session more than the content or actions of the App Extension itself.

Of note, waiting on a breakpoint in the App Extension does keep the session alive.

It goes without saying that it's incredibly frustrating trying to build this App Extension when I can only test it for one minute at a time!

Can provide more details as needed.
Please attach the crash log or a sysdiagnoses so we can debug the crash. Thanks!

One thing I noticed in the video, is you don't need to launch Safari from Xcode when you run the app extension. Safari will reload the extension when it changes if you just build (not run). (With Xcode 11, a clean build is needed if you just change the script resources. That is fixed with the Xcode 12 beta.)
[FB7841818] Safari and Safari TP crash about one minute after using Xcode to run a Safari App Extension target in them, with 100% reproducibility.
 
 
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