035 loop unhandled branch

// Test: Labeled loop with tap observing transitions
//
// Tests that taps work correctly with labeled loops.

const std = @import("std");
~import "$std/taps"

~event counter { n: i32 }
| next { value: i32 }
| done { final: i32 }

~proc counter {
    if (n < 3) {
        return .{ .next = .{ .value = n + 1 } };
    }
    return .{ .done = .{ .final = n } };
}

~event log_iteration { value: i32 }

~proc log_iteration {
    std.debug.print("Iteration: {}\n", .{value});
}

// Tap that fires on counter transitions
~tap(counter -> *)
| next v |> log_iteration(value: v.value)

~event start {}
| ready {}

~proc start {
    return .{ .ready = .{} };
}

// Loop with tap - must handle all branches
~start()
| ready |> #loop counter(n: 1)
    | next v |> @loop(n: v.value)
    | done _ |> _