Fixed crash if going to a declaration in a changed file that is not saved.

src/window.cc

@@ -363,7 +363,18 @@ void Window::create_menu() {
         auto location=notebook.get_current_view()->get_declaration_location();
         if(location.first.size()>0) {
           notebook.open(location.first);
-          notebook.get_current_view()->get_buffer()->place_cursor(notebook.get_current_view()->get_buffer()->get_iter_at_line_index(location.second.line-1, location.second.index-1));
+          auto line=static_cast<int>(location.second.line)-1;
+          auto index=static_cast<int>(location.second.index)-1;
+          auto buffer=notebook.get_current_view()->get_buffer();
+          line=std::min(line, buffer->get_line_count()-1);
+          if(line>=0) {
+            auto iter=buffer->get_iter_at_line(line);
+            while(!iter.ends_line())
+              iter.forward_char();
+            auto end_line_index=iter.get_line_index();
+            index=std::min(index, end_line_index);
+            buffer->place_cursor(buffer->get_iter_at_line_index(line, index));
+            
             while(gtk_events_pending())
               gtk_main_iteration();
             if(notebook.get_current_page()!=-1)
@@ -371,6 +382,7 @@ void Window::create_menu() {
           }
         }
       }
+    }
   });
   menu.action_group->add(Gtk::Action::create("SourceGotoMethod", "Go to Method"), Gtk::AccelKey(menu.key_map["source_goto_method"]), [this]() {
     if(notebook.get_current_page()!=-1) {