iOS Platform:System.Xml.XmlException: Root element is missing

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### [REQUIRED] Please fill in the following fields:

* Unity editor version: 2019.4.27f1
* External Dependency Manager version: 1.2.170
* Source you installed EDM4U: unitypackage
* Features in External Dependency Manager in use: Android Resolver, iOS Resolver, VersionHandler
* Plugins SDK in use: Firebase
* Platform you are using the Unity editor on: Mac

### [REQUIRED] Please describe the question here:

hello, i create the xxxDependencies.xml with code, at first it is an empty file, i call "AssetDatabase.Refresh();", on the Android platform it work well, by on iOS platform, it will log error "System.Xml.XmlException: Root element is missing.", but it will not affect my project, i think on iOS platform it can be done as same as Android platform(when the xxx.xml is empty, it will not parse the file or not log the error), thanks!