resolved #75

Author: 喻斌

src/CatLib.Core/Support/Util/Extension/StreamExtension.cs

@@ -63,8 +63,14 @@ public static long AppendTo(this Stream source, Stream destination, byte[] buffe
         /// <returns>字符串</returns>
         public static string ToText(this Stream source, Encoding encoding = null, bool closed = true)
         {
+            Guard.Requires<ArgumentNullException>(source != null);
             try
             {
+                if (!source.CanRead)
+                {
+                    throw new RuntimeException($"Can not read stream, {nameof(source.CanRead)} == false");
+                }
+
                 encoding = encoding ?? Util.Encoding;
                 var memoryStream = source as MemoryStream;
                 if (memoryStream != null)