103 resume body discard

// ============================================================================
// Test 510_103: MUST_FAIL — handler body is `_` discard but the branch
// declares a resume type. The handler fn must produce a value of the
// resume type; a discard produces nothing.
// ============================================================================

~pub event prompt_user { question: []const u8 }
! ask []const u8 -> []const u8
| done []const u8

~proc prompt_user|zig {
    const reply = ask(question);
    return .{ .done = reply };
}

~prompt_user(question: "?")
! ask _ |> _
| done _ |> _