Why is connecting to SharePoint throwing an error

public bool IsAuth(string gName)
{
    _hostWebUrl = "http://myweb"; //the location where the app is being deployed
    //Retreiving the current context
    //Opening a current web and creating a instance
    try
    {
        using (var context = new ClientContext(_hostWebUrl))
        {
            //GroupCollection siteGroups = context.Web.SiteGroups;
            User user = context.Web.CurrentUser;
            GroupCollection userGroups = user.Groups;

            context.Load(user);
            context.Load(userGroups);
            context.ExecuteQuery();

            foreach (Group group in userGroups)
            {
                //Checking the group
                if (group.Title.Contains(gName))
                    return true;
            }
        }
    }
    catch (Exception ex)
    {
        string error = ex.Message;
        return false;
    }
    return false;
}

I am calling the function like this: bool isAdmin = IsAuth("Adm");

I am getting the following error in the following line (using (var context = new ClientContext(_hostWebUrl))):

ServerVersion = 'context.ServerVersion' threw an exception of type 'Microsoft.SharePoint.Client.PropertyOrFieldNotInitializedException'

I am getting the following error in the following line (foreach (Group group in userGroups)):

base {System.InvalidOperationException} = {"The property or field 'CanCurrentUserEditMembership' has not been initialized. It has not been requested or the request has not been executed. It may need to be explicitly requested."}

Please help me resolve the error.