我是javascript和nodejs领域的初学者。我试图用nodejs创建一个简单的文件上传项目。此外，我在nodejs中创建了路由，从网页中捕获图像，并使用fetch将其发送到nodejs路由。这是html文件：

<div class="file-upload">
    <div class="image-upload-wrap">
        <input class="file-upload-input" type='file' onchange="readURL(this);" accept="image/*" />
        <div class="drag-text">
        <h3>Drag and drop a file or select add Image</h3>
        </div>
    </div>
    <div class="file-upload-content">
        <div class="file-upload-display">
            <img id="file-upload-image" class="file-upload-image" src="#" alt="your image" />
            <div class="image-title-wrap">
                <button type="button" onclick="removeUpload()" class="remove-image"><i class="fas fa-trash-alt"></i> Remove <span class="image-title">Uploaded Image</span></button>
            </div>
        </div>
    </div>
</div>
<br>
<div class="file-upload-server d-flex justify-content-center">
    <button class="btn btn-expand-lg btn-primary" onclick="uploadFile()"><i class="fas fa-cloud-upload-alt"></i> Upload</button>
</div>

这是我的javascript文件：

async function uploadFile() {
    let img = document.getElementById('file-upload-image').src;
    console.log('Image String Length: ' + img.length);
    const payload = {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json'
        },
        body: JSON.stringify({
            file: img, 
        })
    }
    console.log(`Payload: ${JSON.stringify(payload)}`);

   await fetch('http://localhost:3030/image/uploadimage', payload)
    .then(response => response.json())
    .then(data => {
        console.log('Success:', data);
    })
    .catch((error) => {
        console.error('Error:', error);
    });
}

这里的图像是base64编码的字符串，我将其传递给我的nodejs路由。
单击“上载”按钮时，出现以下错误：

我用一个大小为5.72kb的图像测试了这段代码，它可以正常工作。但是当我尝试上传一个81.7kb大小的图像时，它失败了，出现了这个错误。
这是nodejs路由：

router.use(imageupload({
   limits: { fileSize: 50 * 1024 * 1024 },
}));

router.use(express.urlencoded({limit: '50mb', extended: true}));
router.use(express.json());

const decodeBase64Image = (dataString) => {
  let matches = dataString.match(/^data:([A-Za-z-+\/]+);base64,(.+)$/),
  response = {};
  if (matches.length !== 3) {
    return new Error('Invalid input string');
  }
  response.type = matches[1];
  response.data = Buffer.from(matches[2], 'base64');
  return response;
}

router.post('/uploadimage', cors(corsOptions), async (req, res) => {
     let decodedImage = decodeBase64Image(req.body.file); 
     let imageBuffer = decodedImage.data;
     let type = decodedImage.type;
     let extension = mime.getExtension(type);
     let NewImageName =  Math.random().toString(36).substring(7);
     let fileName = 'image-' + NewImageName + '.' + extension;
     try {
           fs.writeFile(`${path.join(__dirname, '../')}/public/uploads/${fileName}`, 
           imageBuffer, function(err) {
           if(err) throw err;
           console.log('The file was uploaded successfully');
           return res.status(200).json({status: 'success', message: 'File uploaded successfully'});
    });
    } catch(err) { 
          console.log(err);
          return res.status(500).send(err);
    }
});

任何关于这方面的帮助或指导都是非常好的。