FIX：Fix the crash that occurred when importing G-code file

Jira：STUDIO-13408

(cherry picked from commit 3810f4edfe086b9500860e59baf35e5568b56977)

src/libslic3r/GCodeReader.hpp

@@ -162,6 +162,11 @@ public:
     float& j()       { return m_position[J]; }
     float  j() const { return m_position[J]; }
 
+    GCodeConfig get_config() const
+    { 
+        return m_config;
+    }
+
 private:
     template<typename ParseLineCallback, typename LineEndCallback>
     bool        parse_file_raw_internal(const std::string &filename, ParseLineCallback parse_line_callback, LineEndCallback line_end_callback);