当有人使用django编辑配置文件并将电子邮件更改为已存在的电子邮件时，我如何发出错误？

from django import forms
from django.core.exceptions import ValidationError
from .models import Config

class ConfigForm(forms.Form):
    email = forms.EmailField()

    def clean_email(self):
        email = self.cleaned_data['email']
        if Config.objects.filter(email=email).exists():
            raise ValidationError("该电子邮件已存在，请输入一个新的电子邮件。")
        return email

def edit_config(request):
    if request.method == 'POST':
        form = ConfigForm(request.POST)
        if form.is_valid():
            # 处理有效的表单数据
            # ...
        else:
            # 处理验证失败的表单数据
            # ...
    else:
        form = ConfigForm()
    
    return render(request, 'edit_config.html', {'form': form})