I have different second genration cloud function on firebase when I call one of them I get an error on the firebase log system: the default firebase app does not exist; thi is my function:

exports.addCustomClaim = onCall({secrets: [privateKey], ...params},
    async (data) => {
      const admin = instantiateFirebase().admin;
      const user = await admin.auth().getUserByEmail(data.data.email);
      console.log("adding claims ", data.data.claims, "to", user.uid);
      try {
        await admin.auth().setCustomUserClaims(user.uid, data.data.claims);
        if (data.data.logoutUser) {
          console.log("logging out user", user.uid);
          await admin.auth().revokeRefreshTokens(user.uid);
        }
        return await {
          message: ` Success!claims ${Object.keys(data.data.claim)}
        have been set on ${data.data.email}`,
        };
      } catch (err) {
        return {error: err, user: user.uid};
      }
    });

this is how I initialize firebase:

const instantiateFirebase = ()=>{
  const privateKey= defineSecret("PRIVATE_KEY");
  const clientEmail = defineString("CLIENT_EMAIL");
  const projectId = defineString("PROJECT_ID");
  const databaseURL = defineString("DATABASE_URL");
  console.log("instantiating firebase");
  if(admin.apps.length===0){
    console.log("no app");
  initializeApp({
    credential: admin.credential.cert({
      privateKey: privateKey.value().replace(/\n/g, "n"),
      projectId: projectId.value(),
      clientEmail: clientEmail.value(),
    }),
    databaseURL: databaseURL.value(),
  });}

  const db = admin.firestore();
  const realtime = admin.database();
  console.log("done");
  return {db, admin, realtime};
};
export {instantiateFirebase};