012 missing required branch

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

// Event with both required and optional branches
~event process { value: u32 }
| success { result: u32 }        // REQUIRED
| ?warning { msg: []const u8 }   // OPTIONAL

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

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