Discord Api JS : Failed to fetch

Question

I'm currently trying to request discord API to get a list of all available channels inside a server, but when I'm running my request I get the error:

Failed to fetch

I really don't know why. I already tried on Postman and with Restsharp in C# and it work perfectly.

The fact is that I succeed to get a list of all guilds with this code :

var detectGuilds= async () => {
  const response = await fetch('https://discord.com/api/users/@me/guilds', {
    method: 'GET',
    headers: {
      'Authorization': 'Bot myBotToken'
    }
  });

  const result = await response.json(); 
}

But I don't know why with the exact same code for channels it failed :

var detectChannels= async () => {
    var idSelectedGuild = dictGuilds[document.getElementById("comboGuilds").value];
    var uri =`https://discord.com/api/guilds/${idSelectedGuild}/channels`;
    var uri2 ="https://discord.com/api/v10/guilds/94055174550578/channels"
    
    const response = await fetch(uri, {
      method: 'GET',
      headers: {
        'Authorization': 'Bot myBotToken',
        //'User-Agent' : 'Mozilla/5.0 (compatible; Discordbot/2.0; +https://discordapp.com)'
      }
    });
  const result = await response.json(); 
  alert(result)
}


---------------------------------------------------------------------
Uncaught TypeError TypeError: Failed to fetch
    at detectChannels (c:\Users\Moi\Downloads\test.html:173:28)
    at onchange (c:\Users\Moi\Downloads\test.html:104:77)
    --- await ---
    at onchange (c:\Users\Moi\Downloads\test.html:104:77)
    at handleMouseUp_ (undefined:586:32)

I spent a lot of time on it and I can't figure out what the problem is

Has anyone got an answer?