Update XCTFail.swift

Author: stephencelis

Sources/XCTestDynamicOverlay/XCTFail.swift

@@ -86,7 +86,7 @@ import Foundation
 
         ━━┉┅
         Note: This failure was emitted from tests running in a host application\
-        \(Bundle.main.bundleIdentifier.map { " (\($0))" }).
+        \(Bundle.main.bundleIdentifier.map { " (\($0))" } ?? "").
 
         This can lead to false positives, where failures could have emitted from live application \
         code at launch time, and not from the current test.