Form errors doesnt work. Django

Question

I read this and have the bug in code - I can send "null" by the form and there is no error message, its just go to 'thanks' page. I can write 'nothing' to the email field, and result will be the same. How to fix it?

models:

class Contact(forms.Form):
    title = forms.CharField(max_length=100)
    message = forms.CharField(max_length=255)
    sender = forms.EmailField()

views:

def contact(request):
    if request.method == 'POST': 
        form = Contact(request.POST) 
        if form.is_valid(): 
            title = form.cleaned_data['title']
            message = form.cleaned_data['message']
            sender = form.cleaned_data['sender']
            return HttpResponseRedirect('/thanks/') 
    else:
        form = Contact()
    return render(request, 'contact.html', {'form': form,})

template:

<form action="/contact/" method="post">
{% csrf_token %}


    {{ form.non_field_errors }}

        {{ form.title.errors }}
        <label for="id_subject">Subject</label>
        {{ form.title }}


        {{ form.message.errors }}
        <label for="id_message">Text</label>
        {{ form.message }}


          {{ form.sender.errors }}
        <label for="id_sender">Email</label>
        {{ form.sender }}


    <p><input type="submit" value="Send" /></p>
</form>

Answer 1

I've got my money on you having mixed tabs and spaces. I haven't seen this in a while - it used to be pretty common!

It appears the return statement is firing no matter what on POST.