how to loop through django form errors after getting them as json with ajax – Jquery ajax

My signup form works fine when there are no errors and saves users correctly but i couldn’t display errors when there are form field errors after getting them with form.errors.as_json

here is the view of the form:

   if request.is_ajax():
       signup_form = SignupForm(request.POST)
       if signup_form.is_valid():
           signup_form.save()
           full_name = signup_form.cleaned_data.get('full_name')
           email = signup_form.cleaned_data.get('email')
           raw_password = signup_form.cleaned_data.get('password1')
           account = authenticate(email=email, password=raw_password)
           login(request, account)
           return JsonResponse({"success" : True}, status=200)
       else:
           return JsonResponse({'success': False},signup_form.errors.as_json() , status=400)

here are the ajax stuff in my javascript file:

 var $signupForm = $('#form-signup');
 $signupForm.submit(function (event) {
   event.preventDefault();
   var $signupData = $signupForm.serialize();
       $.ajax({
         url: "http://localhost:8000",
         method: 'POST',
         data: $signupData,
         success: function() {
           location.reload()
         },
         error: function () {
            // display form errors in a div or console.log them
            // by looping through them
       },
       });
     });

with this code when there are field inputs errors like "pasword is too short" or somthing like that i get error status code 500
and:

‘str’ object is not callable

in my django server terminal

i checked many question about this but none of them helped and most of them were outdated