048 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 i32
| done i32

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

~event log-iteration { value: i32 }

~proc log-iteration|zig {
    std.debug.print("Iteration: {}\n", .{value});
}

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

~event start {}

~proc start|zig {
}

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