Remove cast.

values/decoding/string_decode.go

@@ -61,14 +61,7 @@ func tryDecodeStringDictionary(
 		if err != nil {
 			return 0, err
 		}
-		// Close the underlying reader if it satisifies the `io.ReadCloser` iface.
-		rc, ok := reader.(io.ReadCloser)
-		if ok {
-			// NB(bodu): We don't need to propagate `Close` errors back up because there aren't any.
-			// We have two types of string readers. A bytes reader and a compress reader. The bytes reader
-			// doesn't implement the `io.Closer` iface and the compress reader has no errors when calling `Close`.
-			defer rc.Close()
-		}
+		defer reader.Close()
 		bytesRead, err := xproto.DecodeStringArray(reader, stringArrayProto, decodeBuf)
 		if err != nil {
 			return 0, err