lyb BUGFIX last opaque string must have length

... because the subtree may not be finished and
its children follow.
diff --git a/src/printer_lyb.c b/src/printer_lyb.c
index 5592fa0..fa983ef 100644
--- a/src/printer_lyb.c
+++ b/src/printer_lyb.c
@@ -623,15 +623,15 @@
     /* name */
     LY_CHECK_RET(lyb_write_string(opaq->name.name, 0, 1, out, lybctx));
 
+    /* value */
+    LY_CHECK_RET(lyb_write_string(opaq->value, 0, 1, out, lybctx));
+
     /* format */
     LY_CHECK_RET(lyb_write_number(opaq->format, 1, out, lybctx));
 
     /* value prefixes */
     LY_CHECK_RET(lyb_print_prefix_data(out, opaq->format, opaq->val_prefix_data, lybctx));
 
-    /* value */
-    LY_CHECK_RET(lyb_write_string(opaq->value, 0, 0, out, lybctx));
-
     return LY_SUCCESS;
 }