add option not null check

Author: artidoro

src/Microsoft.ML.Data/DataLoadSave/Text/TextLoader.cs

@@ -1232,6 +1232,7 @@ private static bool TryParseSchema(IHost host, IMultiStreamSource files,
         {
             host.AssertValue(host);
             host.AssertValue(files);
+            host.CheckValue(options, nameof(options));
 
             cols = null;
             error = false;