FIX: check if the filament is unknown

jira: [STUDIO-12085]
Change-Id: Ibf40d7a5106a40385aff5c769e5b7e5cdb866de0
(cherry picked from commit 012b6f2395d66b7b1bdafa3e851ca4b2f874eb23)

src/slic3r/GUI/Widgets/AMSControl.hpp

@@ -194,6 +194,9 @@ public:
     virtual bool Enable(bool enable = true);
     void parse_object(MachineObject* obj);
 
+private:
+    std::string get_filament_id(const std::string& ams_id, const std::string& can_id);
+
 public:
     std::string m_current_select;
 };