012 missing required branch

// ============================================================================
// Test 060b: Missing Required Branch
// Tests that flow_checker catches missing required branches
// ============================================================================

// Event with both required and optional branches
~tor process { value: u32 }
| success u32        // REQUIRED
| ?warning string   // OPTIONAL

// Proc implementation that can return both branches
~proc process|zig {
    if (value > 100) {
        return .{ .warning = "Large value" };
    }
    return .{ .success = value * 2 };
}

// This flow is INVALID - missing required 'success' branch!
~process(value: 10)
// Missing: | success s |> ...