crach android app unity2018 after FB.ActivateApp()

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Checklist

• [v ] I've updated to the latest released version of the SDK
• [v ] I've searched for existing GitHub issues
• [v ] I've looked for existing answers on Stack Overflow, the Facebook Developer Community Forum and the Facebook Developers Group
• [v ] I've read the Code of Conduct
• [ v] This issue is not security related and can safely be disclosed publicly on GitHub

Environment

Describe your dev environment here, giving as many details as possible. If you have them, make sure to include:

• Unity Editor Version: 2018.4.2
• Unity SDK Version: v7.16.0 ~ v7.18.0
• Installation Platform & Verison: Android version 6.0.1

Code Samples & Details

1. install facebook unity latest version in newproject unity2018.4
2. add FB.ActivateApp() in sample

FB.Init(this.OnInitComplete, this.OnHideUnity);

private void OnInitComplete()
{
       this.Status = "Success - Check log for details";
       this.LastResponse = "Success Response: OnInitComplete Called\n";
       string logMessage = string.Format(
                "OnInitCompleteCalled IsLoggedIn='{0}' IsInitialized='{1}'",
                FB.IsLoggedIn,
                FB.IsInitialized);
       LogView.AddLog(logMessage);
       if (AccessToken.CurrentAccessToken != null)
       {
           LogView.AddLog(AccessToken.CurrentAccessToken.ToString());
       }

       //here
       FB.ActivateApp();
}

3. play sample app
4. click FB.init
5. click Login
6. close facebook window
7. repeat 5-6
8. crash java.lang.RuntimeException: Window couldn't find content container view

It will not crash unless call FB.ActivateApp()

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add crash video facebookcrash_20191113.zip

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add sample project onlyfacebook.zip