I don't own an iPad, so I cannot reproduce it myself. The error was caught in production on the device of one of the end users. However, since the code is executed for every scheduler instance it doesn't really matter which example you choose. They all experience the same issue.
Just tested it on Chrome (Windows 10). No problems there. So, as I said before this seems to be a device/browser/os specific issue. I'll leave the rest of the testing up to you guys.
Ok, any idea on the steps to reproduce? We can heavily recommend RootCause for your debugging efforts btw. How do you monitor production bugs currently? https://therootcause.io/
Steps to reproduce should be quite simple. Make sure you have the right device (I don't own any, so I can't check it myself). Hook it up to a debugger and then trigger a "contextmenu" event on the planboard (that is probably a longpress on an iPad, not really sure). I am pretty sure the developers will be able easily find a way to reproduce if they just take a took at the code, especially since this appears to be some custom handler for non-Android touch devices (i.e. it will mostly be targeting Apple products).