getting error string instead of panic

[gaplyk]

What version of Go are you using (go version)?

$ go version
go1.12.5

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

i don't know environment behind playground.

What did you do?

https://play.golang.org/p/jRplZeblynF

What did you expect to see?

I expect to see panic as panic not as an error

What did you see instead?

string error

[bcmills]

Duplicate of #28150