Cannot read properties of undefined (reading 'send')

Problem "Uncaught TypeError: Cannot read properties of undefined (reading 'send')" when i trying run a function with "eel.nice()" inside.

app.py

@eel.expose
def nice():
    print("GG")

topnav.html

        checkBox = document.getElementById('flexSwitchCheckDefault').addEventListener('click', event => {
            if(event.target.checked) {
                eel.nice()
                document.getElementById("languageSelect").setAttribute("disabled", '');
            }
            else {
                eel.nice()
                document.getElementById("languageSelect").removeAttribute("disabled");
            }
        });

This problem only appears if you put another code file using jquery. Is there an option when importing another html file to fix the problem or will EEL only work directly? Script in index.html:

 $(function(){
      $("#includedContent").load("topnav.html"); 
    });

Desktop

• OS: Windows 10 Pro
• Browser: chrome
• Version 110.0.5468.0, canary (64 bit)