Allow ESC to be binded to custom action, when not in tab complete, at least when nothing being inputed

I am using reedline in my rfm file manager, to let user manipulate files shown in GUI with commands in terminal emulator. But i cannot keybind ESC to my custom code, it's said that ESC is used by reedline. I see that when i use tab completion and menu, ESC can cancel the menu. But at least when i start a new readline call and nothing has being inputted, i see nothing happens with ESC. I just need ESC for my custom action here: I want to use ESC to cancel the file selection in file manager GUI. Without this, i have to switch focus to the GUI window, ESC to cancel file selection and switch focus back. Currently, i am using ALT+E keybinding as an alternative, but it's not easy to remember as ESC.

Start by tracing how reedline handles ESC, especially the existing tab-completion and menu cancellation paths. Verify the behavior for an empty input outside completion or menus, then make completion cancellation continue to work while allowing the configured custom action to run in that case.