how to create image-url instead of base-64 (using summernote in express)?

Win10 , VScode
I am practicing making a bulletin board using a web editor called summernote.
I want to add image upload function to summetnote
but I don’t know how. I’d really appreciate it if the teachers could help me.
First, here is my project link.
In particular, please refer to routes/topic.js and views/create.ejs.
ejs file

$(document).ready(function(){
  $('#summernote').summernote({
    width: 800,
    height: 300,
    minHeight: null,
    maxHeight: null,
    focus: true,
    onImageUpload: function(files, editor, welEditable) {
      sendFile(files[0],editor,welEditable);
    }
  })
})

function sendFile(file,editor,welEditable) {
  data = new FormData();
  data.append('file',file);
  $.ajax({
    data: data,
    type: "POST",
    url: "/create_process",
    cache: false,
    contentType: false,
    processData: false,
    success: function(url) {
      editor.insertImage(welEditable, url);
    }
  });
}

serverside

let storage = multer.diskStorage({
  destination: (req,file,cb) => {
    cb(null,"../public/images");
  },
  filename: (req,file,cb) => {
    let ext = path.extname(file.originalname);
    cb(null,path.basename(file.originalname, ext) + "-" + Date.now() + ext);
  }
});

let upload = multer({storage: storage});

router.post('/create_process', upload.single('file') ,(req,res) => {
  console.log(req.file);
});

However, the following error occurs in the terminal

Field value too long

I think it’s because of the base-64.
How can I create a simple image-url and upload an image?