How to terminate My function, it is working but never ending

Question

I use the api mangopay for my app. The function to transfered worked but it never end until I refresh my page. I have no error code, the function still working but we can't get the message: 'the money is transfered'

Maybe I forgot something on my function ?

transfertMangoReferent: (req, res) => {
    Serveur.findOne(
      { email: req.body.email },
      "mangoWallet abonne",
      (err, user) => {
        if (user.abonne === true) {
          api.Transfers.create(
            {
              AuthorId: req.user.mangoID,

              DebitedFunds: {
                Currency: "EUR",
                Amount: req.body.amount * 100,
              },
              Fees: {
                Currency: "EUR",
                Amount: req.body.amount * 100 * 0.15,
              },

              DebitedWalletId: req.user.mangoWalletReferent,
              CreditedWalletId: user.mangoWallet,
              Tag: "Versement du pot Commun",
            },
            (model) => {
              (error) => {
                if (error) {
                  res.status(500).json({
                    message: "An error has occured with MANGO users",
                  });
                  
                }else{
                  res.json(model)
                }
              };
            }
          );
        } else {
          api.Transfers.create(
            {
              AuthorId: req.user.mangoID,

              DebitedFunds: {
                Currency: "EUR",
                Amount: req.body.amount * 100,
              },
              Fees: {
                Currency: "EUR",
                Amount: req.body.amount * 100 * 0.25,
              },

              DebitedWalletId: req.user.mangoWalletReferent,
              CreditedWalletId: user.mangoWallet,
              Tag: "Versement du pot Commun",
            },
            (model) => {
              (error) => {
                if (error) {
                  res.status(500).json({
                    message: "An error has occured with MANGO users",
                  });
                  
                } else {
                  res.json(model)
                }
              };
            }
          );
        }
      }
    );
  },

On my network when i click to my button validate i have just the code 200

I can give you also my fetch in a react js

<Button
            className="CollectButton"
            type="submit"
            onClick={() => {
              const headers = new Headers({
                "Content-Type": "application/json",
                Authorization: "bearer " + localStorage.getItem("token"),
              });
              const data = {
                email: element.serveurMail,
                amount: this.state.referent.amount,
              };
              const options = {
                method: "POST",
                headers: headers,
                body: JSON.stringify(data),
              };

              fetch("https://back-end.osc-fr1.scalingo.io/serveur/referentTransfert", options)
                .then((response) => {
                  return response;
                })
                .then(
                  (data) => {
                    console.log(data);
                  },

                  (error) => {
                    console.log(error);
                  }
                );
            }}
          >
            Envoyez
          </Button>