Error: AttributeError: 'NoneType' object has no attribute 'split'. What's the matter?

Question

Django

Let's start with the fact that I'm a beginner. I created a simple form for sending data to the database on the site. Everything sends well, but this error constantly comes up (a lot of text and at the end AttributeError: 'NoneType' object has no attribute 'split'. )
It occurs already when the server starts after a few seconds.
view:

from django.shortcuts import render
from .forms import PersonForm
from django.http import HttpResponse, HttpResponseRedirect
 #Create your views here.

def index(request):
    form = PersonForm (request.POST or None)
    if request.method == "POST" and form.is_valid():
        form.save()
    return render(request, "index.html", {'form': form})

model:

from django.db import models

# Create your models here.


class Person(models.Model):
    name = models.CharField(max_length=20,verbose_name='Имя')
    email = models.EmailField(verbose_name='E-mail')
    tel = models.CharField(max_length=12,verbose_name='Телефон')

    class Meta:
        verbose_name = u'Пользователь'
        verbose_name_plural = u'Пользователи'

forms.py :

from django import forms
from .models import Person


class PersonForm (forms.ModelForm):
    class Meta:
        model = Person
        exclude = [""]

index.html

<form action="" method="post">
    {% csrf_token %}
    {{ form.as_p }}
    <input type="submit" value="Присоединиться">
</form>

Help, pliz, what does this get out, and how to fix it?