[Minor] Fix plain Lua compatibility

diff --git a/lualib/lua_fuzzy.lua b/lualib/lua_fuzzy.lua
index 683c573728ec36012c8b6b8b22e0aa7382de49d6..8547a5dbc6a1428bfe0494c1edd411d45d0a93fe 100644 (file)
--- a/lualib/lua_fuzzy.lua
+++ b/lualib/lua_fuzzy.lua
@@ -245,8 +245,15 @@ local function mime_types_check(task, part, rule)
   if not t then return false, false end
 
   local ct = string.format('%s/%s', t, st)
+
+  local detected_ct
   t,st = part:get_detected_type()
-  local detected_ct = string.format('%s/%s', t, st)
+  if t then
+    detected_ct = string.format('%s/%s', t, st)
+  else
+    detected_ct = ct
+  end
+
   local id = part:get_id()
   lua_util.debugm(N, task, 'check binary part %s: %s', id, ct)