Reject END { break } for Ruby 3.5

[Earlopain]

For [Bug #20409]

[kddnewton]

Do we know if this is mergable yet?

[Earlopain]

I think this was OKed in a dev meeting. I will check and clean this up

[Earlopain]

https://github.com/ruby/dev-meeting-log/blob/f76ba7e3f69feaff70672f0077976d7f63313601/2025/DevMeeting-2025-11-13.md#bug-20409-missing-reporting-some-invalid-breaks-kddnewton

I think this is accepted, END { break } at least? Can't tell for sure. For reference, I tested again how it currently behaves:

END
return - runtime error
break - runtime error
next - ok

BEGIN
return - ok
break - syntax error
next - syntax error

Currently I have return in end still accepted but it also leads to a runtime error. I guess this can be merged as is after rebase, what do you think?