BaseModelAnonymiser crashes on TextField

[jhonatan-lopes]

When trying to anonymise TextFields, the anonymiser crashes with:

 File "/app/.venv/lib/python3.10/site-packages/birdbath/management/commands/run_birdbath.py", line 49, in handle
    raise Exception(errors)
Exception: [TypeError("unsupported operand type(s) for +: 'NoneType' and 'int'")]

Reproducing

Create a new model with a TextField and an anonymiser targeting it:

from django.db import models
from birdbath.processors import BaseModelAnonymiser

class MyModel(models.Model):
    text_field = models.TextField()


class MyAnonymiser(BaseModelAnonymiser):
    model = MyModel
    anonymise_fields = ["text_field"]

And then run ./manage.py run_birdbath to see the error.