(write_error): Read error is an error, not just a warning.

src/buffer.c

@@ -1080,7 +1080,7 @@ write_error (ssize_t status)
 static void
 read_error (void)
 {
-  WARN ((0, errno, _("Read error on %s"), *archive_name_cursor));
+  ERROR ((0, errno, _("Read error on %s"), *archive_name_cursor));
 
   if (record_start_block == 0)
     FATAL_ERROR ((0, 0, _("At beginning of tape, quitting now")));