They only needed to test with the latest Electron at the time of release (or indeed, any chance version - they're all affected - but latest is a reasonable baseline). If they had, they would've seen this.
There are patches out now, but only after Apple released the OS to the entire team world and people reported the issue to the Electron team.
Imo, Electron is sufficiently popular that somebody should test at least one Electron app on a major new OS version sometime before releasing it as done! Any app would've worked, and there's plenty of popular ones, as this post shows.