Wie kann ich mein live Video sehen

Ich kann bei folgender Funktion nicht mein Video sehen und ich weiß nicht warum:

function renderMain() {
   bigVideo.innerHTML = "";
   const userKey = currentBig;
   if (userKey === "local") {
       const vid = document.createElement("video");
       vid.autoplay = true;
       vid.muted = true;
       if (localVideoOn) {
           vid.srcObject = localStream;
           vid.play().catch(err => alert("Autoplay blockiert:", err));
       } else {
           // Platzhalter, statt video
           const ph = document.createElement("div");
           ph.classList.add("placeholder");
           ph.textContent = username.charAt(0).toUpperCase();
           bigVideo.append(ph);
          return;
      }
      bigVideo.append(vid);
   } else {
     const p = peers[userKey];
     if (p.remoteStream && !p.user.camOff) {
       const vid = document.createElement("video");
       vid.srcObject = p.remoteStream;
       vid.autoplay = true;
       bigVideo.append(vid);
     } else {
       const ph = document.createElement("div");
       ph.classList.add("placeholder");
       ph.textContent = p.user.username[0];
       bigVideo.append(ph);
     }
     // Name & Mic-Icon
     const info = document.createElement("div");
     info.style.position = "absolute";
     info.style.bottom = "5px";
     info.style.left = "5px";
     info.style.color = "#fff";
     info.textContent = p.user.username;
     bigVideo.append(info);
     if (p.user.audioOff) {
       const mic = document.createElement("span");
       mic.style.position="absolute";
       mic.style.bottom="5px";
       mic.style.right="5px";
       mic.textContent="🔇";
       bigVideo.append(mic);
     }
   }

   // Small preview
   smallPreview.innerHTML = "";
   const previewStream = localVideoOn ? localStream : null;
   const vid2 = document.createElement("video");
   if (previewStream) {
       vid2.srcObject = previewStream;
       vid2.play().catch(err => alert("Preview autoplay blockiert:", err));
   }
   vid2.autoplay = vid2.muted = true;
   smallPreview.append(vid2);
 }

Wie kann ich das Problem lösen? Das ist der komplette Code, falls notwendig:

// webrtc-client.js
(async ()=> {
 const socket = io({ query: { room, username, gender }});
 const mainC = document.getElementById("mainContainer");
 const usersC = document.getElementById("usersContainer");
 const bigVideo = document.getElementById("bigVideo");
 const smallPreview = document.getElementById("smallPreview");
 const actionBar = document.getElementById("actionBar");
 const btnMic = document.getElementById("btnToggleMic");
 const btnCam = document.getElementById("btnToggleCam");
 const btnSwitch = document.getElementById("btnSwitchCam");
 const toUsers = document.getElementById("toUsers");
 const toMain = document.getElementById("toMain");
 const usersGrid = document.getElementById("usersGrid");

 let localStream;
try {
 localStream = await navigator.mediaDevices.getUserMedia({ video: true, audio: true });
} catch (err) {
 alert("Fehler beim Zugriff auf Kamera/Mikrofon:\n" + err.message);
 return; // ggf. abbrechen
}

 let localVideoOn = true, localAudioOn = true;
 let peers = {}, currentBig = null;

 // Helper: Video-Element erstellen oder Platzhalter
 function makeVideoEl(stream, user) {
   const container = document.createElement("div");
   container.classList.add("userBox");
   const mediaEl = stream
     ? Object.assign(document.createElement("video"), { srcObject: stream, autoplay:true, muted: user.isLocal })
     : (() => {
         const p = document.createElement("div");
         p.classList.add("placeholder");
         p.textContent = user.username[0];
         return p;
       })();
   container.append(mediaEl);

   // Icons
   if (!stream && user.camOff) {
     // show placeholder (already)
   }
   if (user.audioOff) {
     const mic = document.createElement("span");
     mic.classList.add("micIcon");
     mic.textContent = "🔇";
     container.append(mic);
   }
   const gender = document.createElement("span");
   gender.classList.add("genderIcon");
   gender.textContent = user.gender === "m" ? "♂️" : user.gender === "w" ? "♀️" : "⚧️";
   container.append(gender);

   const info = document.createElement("div");
   info.classList.add("userInfo");
   info.textContent = user.username;
   container.append(info);

   return container;
 }

 // Umschalten zwischen Main- und Users-View
 toUsers.onclick  = ()=> mainC.classList.replace("active",""), usersC.classList.add("active");
 toMain.onclick   = ()=> usersC.classList.replace("active",""), mainC.classList.add("active");

 // ActionBar toggle
 bigVideo.onclick = ()=> actionBar.classList.toggle("visible");

 // Button-Events
 btnMic.onclick = () => {
   localAudioOn = !localAudioOn;
   localStream.getAudioTracks()[0].enabled = localAudioOn;
   btnMic.textContent = localAudioOn? "🎤":"🔇";
 };
 btnCam.onclick = () => {
   localVideoOn = !localVideoOn;
   localStream.getVideoTracks()[0].enabled = localVideoOn;
   btnCam.textContent = localVideoOn? "📷":"🚫";
   renderMain(); // Platzhalter ggf. neu zeichnen
 };
 btnSwitch.onclick = () => {
   // Bei 2 Teilnehmern: Video-Swapping
   if (Object.keys(peers).length === 1) {
     const otherId = Object.keys(peers)[0];
     currentBig = currentBig === otherId ? "local" : otherId;
     renderMain();
   }
 };

 // Peer-Verbindungen aufbauen (für jeden weiteren Teilnehmer eins)
 socket.on("roomData", async data => {
   // data: { socketId: { userName, gender } , … }
   // entfernte Verbindungen bereinigen
   for (let id in peers) {
     if (!data[id]) { peers[id].close(); delete peers[id]; }
   }
   // neue Verbindungen
   for (let id in data) {
     if (id === socket.id) continue;
     if (peers[id]) continue;
     const pc = new RTCPeerConnection();
     localStream.getTracks().forEach(t => pc.addTrack(t, localStream));

     pc.onicecandidate = e => e.candidate && socket.emit("signal", { to:id, from:socket.id, data:e.candidate });
     pc.ontrack = e => {
       peers[id].remoteStream = e.streams[0];
       renderMain();
       renderUsers();
     };

     const offer = await pc.createOffer();
     await pc.setLocalDescription(offer);
     socket.emit("signal", { to:id, from:socket.id, data:pc.localDescription });

     peers[id] = { pc, user: data[id], remoteStream: null };
   }

   // Wer spricht? (optional: per Audio-Level-Detection)
   // Für 1 oder 2: currentBig setzen
   if (Object.keys(peers).length <= 1) {
     currentBig = Object.keys(peers)[0] || "local";
   }
   renderMain();
   renderUsers();
 });

 socket.on("signal", async ({ from, data }) => {
   const p = peers[from];
   if (!p) return;
   if (data.type) {
     await p.pc.setRemoteDescription(data);
     if (data.type === "offer") {
       const answer = await p.pc.createAnswer();
       await p.pc.setLocalDescription(answer);
       socket.emit("signal", { to: from, from: socket.id, data: p.pc.localDescription });
     }
   } else {
     await p.pc.addIceCandidate(data);
   }
 });

 // Render-Funktionen
 function renderMain() {
   bigVideo.innerHTML = "";
   const userKey = currentBig;
   if (userKey === "local") {
       const vid = document.createElement("video");
       vid.autoplay = true;
       vid.muted = true;
       if (localVideoOn) {
           vid.srcObject = localStream;
           vid.play().catch(err => alert("Autoplay blockiert:", err));
       } else {
           // Platzhalter, statt video
           const ph = document.createElement("div");
           ph.classList.add("placeholder");
           ph.textContent = username.charAt(0).toUpperCase();
           bigVideo.append(ph);
          return;
      }
      bigVideo.append(vid);
   } else {
     const p = peers[userKey];
     if (p.remoteStream && !p.user.camOff) {
       const vid = document.createElement("video");
       vid.srcObject = p.remoteStream;
       vid.autoplay = true;
       bigVideo.append(vid);
     } else {
       const ph = document.createElement("div");
       ph.classList.add("placeholder");
       ph.textContent = p.user.username[0];
       bigVideo.append(ph);
     }
     // Name & Mic-Icon
     const info = document.createElement("div");
     info.style.position = "absolute";
     info.style.bottom = "5px";
     info.style.left = "5px";
     info.style.color = "#fff";
     info.textContent = p.user.username;
     bigVideo.append(info);
     if (p.user.audioOff) {
       const mic = document.createElement("span");
       mic.style.position="absolute";
       mic.style.bottom="5px";
       mic.style.right="5px";
       mic.textContent="🔇";
       bigVideo.append(mic);
     }
   }

   // Small preview
   smallPreview.innerHTML = "";
   const previewStream = localVideoOn ? localStream : null;
   const vid2 = document.createElement("video");
   if (previewStream) {
       vid2.srcObject = previewStream;
       vid2.play().catch(err => alert("Preview autoplay blockiert:", err));
   }
   vid2.autoplay = vid2.muted = true;
   smallPreview.append(vid2);
 }

 function renderUsers() {
   usersGrid.innerHTML = "";
   // Alle Fremd-User
   Object.entries(peers).forEach(([id, { user, remoteStream }]) => {
     const box = makeVideoEl(remoteStream, { ...user, audioOff: user.audioOff, camOff: !remoteStream });
     usersGrid.append(box);
   });
   // Mein kleines Video oben rechts
   const meBox = makeVideoEl(localStream, { username, gender, isLocal:true, audioOff: !localAudioOn, camOff: !localVideoOn });
   meBox.id = "meBox";
   usersGrid.append(meBox);
 }

 // Initial render
 renderMain();
 renderUsers();
})();