turtle-wow: only extend autoshift if module is enabled

modules/turtle-wow.lua

@@ -10,7 +10,9 @@ pfUI:RegisterModule("turtle-wow", "vanilla", function ()
     pfUI_locale["enUS"]["debuffs"]["Hand of Reckoning"] = { [0] = 3.0 }
 
     -- add tree of life druid form to autoshift
-    table.insert(pfUI.autoshift.shapeshifts, "ability_druid_treeoflife")
+    if pfUI.autoshift then
+      table.insert(pfUI.autoshift.shapeshifts, "ability_druid_treeoflife")
+    end
 
     -- disable turtle wow's map window implementation
     if pfUI.map and not Cartographer and not METAMAP_TITLE then