ltj-ruby.lua: cache_handle can be nil

diff --git a/src/ltj-ruby.lua b/src/ltj-ruby.lua
index 4007fba..145f332 100644 (file)
--- a/src/ltj-ruby.lua
+++ b/src/ltj-ruby.lua
@@ -571,7 +571,7 @@ local post_lown
 do
    local function write_aux(wv, num)
       local id = has_attr(wv, attr_ruby_id)
-      if id>0 then
+      if id>0 and cache_handle then
         cache_handle:write(
                    'luatexja.ruby.old_break_info['
                       .. tostring(id) .. ']=' .. num