Webextension thunderbird get attachment

Question

First of all I want to apologize if this question may seem too simple but I haven't found any solution since yesterday and I'm not very good at javascript. I want to create a personal Thunderbird addons that will communicate with an application I have created, for that I need to have a file attached in a message. I used these commands

    console.log("attachment : " + test);
    var test1 = await browser.compose.listAttachments(tab.id);
    console.log("attachments : " + test1.toString());

to learn the language a bit better and see what was returned and the return message is: TypeError: browser.compose.ComposeAttachment is undefined

And listAttachments does not return anything

Complete code :

browser.composeAction.onClicked.addListener(async (tab) => {

    var file = new File(["foo"], "foo.pdf", {
        type: "application/pdf",
    });

    console.log("File : " + file);

    browser.compose.addAttachment(tab.id, {
        file
    })

    var test = await browser.compose.ComposeAttachment.getFile();
    console.log("attachment : " + test);

    var test1 = await browser.compose.listAttachments(tab.id);
    console.log("attachments : " + test1.toString());

 
}); 

Thanks to the research I did, I correctly configured the manifest.json with the compose permission. I would like to know if someone can explain to me how to use these functions in this context.

Best regards