Dispatch on returned type would be a pretty intense change to julia’s semantics.
(But pretty cool)
And introducing a new error for that particular case would be breaking.
Always worth a read of “Julia is not a that stage of development anymore.”
The bottom line is that the general feel of how Julia works is done. Finito. Finished. Julia
Maybe that is not so weird that it is out of consideration for Julia 2.0.
Or maybe it is.