In yet other words: [yieldto] is a "rigid connector" like [tailcall], keeping the current branch of the current stack tree, while [coroutine/yield] forks a branch off.
For this reason, an error in a coroutine "pops up" back to the closest [coroutine] or resumption, ie the coro floor of the current branch.
So, not a bug, after all.
Agreed ?