Google Chrome extension content_script sendResponse does not work

Question

First I made a query from popup

requestForCodeMirrorElement(){ 
    chrome.tabs.query({active: true, currentWindow: true}, (tabs) => {
      chrome.tabs.sendMessage(tabs[0].id, {name: "GetChosenCodeMirrorText"}, (response) => {
        console.log(response);
      });
    });
  }

Then I add this in my content_script

chrome.runtime.onMessage.addListener(
  function(request, sender, sendResponse) {

    if (request.name == "GetChosenCodeMirrorText"){
        var codeMirrorContent='empty';

        document.addEventListener('GetContent', function (e){
            codeMirrorContent =e.detail.content;
            console.log(codeMirrorContent);
            sendResponse({chosenCodeMirrorText: codeMirrorContent});
        });


        var s = document.createElement('script');
        s.src = chrome.extension.getURL('get_codemirror_script.js');
        (document.head||document.documentElement).appendChild(s);
        s.onload = function() {
            s.parentNode.removeChild(s);
        };
    }
    return true;
});

I wrote this file called get_codemirror_script.js and it has been added to manifest.json.

When I test the code in Chrome, I get codeMirrorContent in console so I think get_codemirror_script.js does not have any problem.

When I change my content_script to this:

chrome.runtime.onMessage.addListener(
  function(request, sender, sendResponse) {

    if (request.name == "GetChosenCodeMirrorText"){
        var codeMirrorContent='empty';
        
        sendResponse({chosenCodeMirrorText: "forTest"});
        
        document.addEventListener('GetContent', function (e){
            codeMirrorContent =e.detail.content;
            console.log(codeMirrorContent);
        });


        var s = document.createElement('script');
        s.src = chrome.extension.getURL('get_codemirror_script.js');
        (document.head||document.documentElement).appendChild(s);
        s.onload = function() {
            s.parentNode.removeChild(s);
        };
    }
});

I get "forTest" in popup console. So I guess there should be some problem with sendRequest. How can I fix it?

---

UPDATE: Just for reference, I used to inject embedded code (see Insert code into the page context using a content script) instead of injecting file like what I described above. And that time it works fine.