在react js中上传文件到ipfs时出错

Question

我尝试在 React js UI 中将图像上传到 ipfs。当使用添加按钮添加图像时，它可以工作，但是当单击提交按钮时，会出现下一个错误 “未捕获（承诺中）错误：意外输入：null normalise-candidate-single.js:16”，然后将 ipfs 的返回哈希存储在 hypeledger 结构中

谁可以帮助我？

我的App.js文件如下
**

import React, { Component } from 'react';
import './App.css';
import { create } from 'ipfs-http-client'

const ipfs = create('http://localhost:5001') 


class App extends Component {
   constructor(props) {
    super(props)
    this.state = {
      buffer: null
    }
  }
 
  
 captureFile = (event) => {
   event.preventDefault()
   //process file for IPFS...
   const file = event.target.files[0]
   const reader = new window.FileReader()
   reader.readAsArrayBuffer(file)
   reader.onloaded = () => {
     this.setState(('buffer', Buffer(reader.result)))
   }

 }
 onSubmit = (event) => {
   event.preventDefault()
   console.log("submiting the form....")
   ipfs.add(this.state.buffer, (error, result) => {
    console.log('Ipfs result', result)
    if(error) {
      console.error(error)
      return
    }
 })
}
 

  
      
      render() {
        return (
                                    
         
      <div>
        
        <div className="container-fluid mt-5">
          <div className="row">
            <main role="main" className="col-lg-12 d-flex text-center">
              <div className="content mr-auto ml-auto">
                 
                <h2>Change Logo</h2>
                <form onSubmit={this.onSubmit} >
                  <input type='file' onChange={this.captureFile} />
                  <input type='submit'/>
                </form>
              </div>
            </main>
          </div>
        </div>
      </div>
    );
  }
}
              
 export default App;
 

**