title: SeriLog MongoDB databaseName is null
body: <p>I am trying to write to a MongoDB hosted locally using Serilog. </p>
  
  <p>I'm getting an error when trying to start the application</p>
  
  <p><strong>ArgumentNullException: Value cannot be null. (Parameter 'databaseName')
  MongoDB.Driver.Core.Misc.Ensure.IsNotNull(T value, string paramName)</strong></p>
  
  <p>My Serilog code is </p>
  
  <pre><code>WriteTo.MongoDB(databaseUrl: "mongodb://##.##.#.#:#####/", collectionName: "TDSlog")
  </code></pre>