[Bug]: registerStringProtocol crashes the entry app

[mahnunchik]

Preflight Checklist

I have read the Contributing Guidelines for this project.
I agree to follow the Code of Conduct that this project adheres to.
I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Electron Version

9.4.4, 10.4.2, 11.4.2, 12.0.2

What operating system are you using?

macOS

Operating System Version

11.2.2

What arch are you using?

x64

Last Known Working Electron version

Expected Behavior

App works

Actual Behavior

App crashes

Testcase Gist URL

https://gist.github.com/mahnunchik/aaef0dffd6c03020b80c58925f31d2af

But removing callback call from the registerStringProtocol handler keeps app working.

[mahnunchik]

The similar issue was before, but should be fixed. It seems the bug was introduces again:

• Electron crashes with custom string / buffer protocol + custom http protocol #10432
• IO thread crash using custom protocol #9342
• Fix crash in custom protocols caused by bad callback exec #10918

[mahnunchik]

@pfrazee previous fix is from your commit, maybe you know whats wrong with registerStringProtocol method ?

[codebytere]

Duplicate of #28407

[mahnunchik]

@codebytere are you sure that it is related with #28407 ? In my case app crashes after click and handle the custom protocol link.

[pfrazee]

No idea if it's the same issue, I was working with pretty limited understanding. I detailed everything I knew/understood in the PR