Merge pull request #450 from s-hadinger/bytes_avoid_crash_item

Avoid crash in item

src/be_byteslib.c

@@ -1180,6 +1180,7 @@ static int m_item(bvm *vm)
 {
     int argc = be_top(vm);
     buf_impl attr = bytes_check_data(vm, 0); /* we reserve 4 bytes anyways */
+    check_ptr(vm, &attr);
     if (argc >=2 && be_isint(vm, 2)) {  /* single byte */
         int index = be_toint(vm,2);
         if (index < 0) {