问依赖项注入IApplicationEnvironment错误

EN

public Startup(IApplicationEnviroment appEnv)
{
    var builder = new ConfigurationBuilder()
        .SetBasePath(appEnv.ApplicationBasePath)
        .AddJsonFile("config.json")
        .AddEnvironmentVariables();

    Configuration = builder.Build();
}

#if DEBUG
        services.AddScoped<IMailService, DebugMailService>();
#else
        services.AddScoped<IMailService, RealMailService>();
#endif

public interface IMailService
{
    bool SendMail(string to, string from, string subject, string body);
}

public class DebugMailService : IMailService
{
    public bool SendMail(string to, string from, string subject, string body)
    {
        Debug.WriteLine($"Sending mail: To: {to}, Subject: {subject}");
        return true;
    }
}