ReaderDictionary: Handle all dictionaries being disabled better. (#7737)

By showing a warning, instead of not passing any -u flag to sdcv and letting it query *all* dictionaries if FS order...

Co-authored-by: Frans de Jonge <fransdejonge@gmail.com>

frontend/apps/reader/modules/readerdictionary.lua

@@ -800,7 +800,7 @@ function ReaderDictionary:startSdcv(word, dict_names, fuzzy_search)
         -- dummy results
         final_results = {
             {
-                dict = "",
+                dict = _("Not available"),
                 word = word,
                 definition = lookup_cancelled and _("Dictionary lookup interrupted.") or _("No results."),
                 no_result = true,
@@ -849,6 +849,22 @@ function ReaderDictionary:stardictLookup(word, dict_names, fuzzy_search, box, li
         return
     end
 
+    -- If the user disabled all the dictionaries, go away.
+    if dict_names and #dict_names == 0 then
+        -- Dummy result
+        local nope = {
+            {
+                dict = _("Not available"),
+                word = word,
+                definition = _("There are no enabled dictionaries.\nPlease check the 'Dictionary settings' menu."),
+                no_result = true,
+                lookup_cancelled = false,
+            }
+        }
+        self:showDict(word, nope, box, link)
+        return
+    end
+
     self:showLookupInfo(word, self.lookup_msg_delay)
 
     self._lookup_start_tv = UIManager:getTime()