007 reject continuation without branch handler

// TEST: Reject a continuation provided without any branch handler.
//
// Every continuation in a flow must be a response to a named branch of the
// preceding event. Bare `|>` tries to chain the next event without naming
// which branch it handles — there is no implicit "positive case," no
// default, no fallback. Every branch must be named explicitly.
//
// Legal:   | ok |> next()
// Legal:   | err _ |> next()
// Illegal: |> next()           (no branch handler — which branch is this?)

~event ping {}
| ok
| err []const u8

~proc ping {
    return .{ .ok = .{} };
}

~ping()
|> _
| err _ |> _

pub fn main() void {}