Investigate & Fix errors on file upload

[mammuth]

According to Sentry, some users experienced errors when uploading their clipping's file.

• https://sentry.io/organizations/personal-c6b/issues/2351272823/

ValueError: A string literal cannot contain NUL (0x00) characters.

ValueError: A string literal cannot contain NUL (0x00) characters.
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...
  File "django/db/models/query.py", line 1121, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "django/db/models/query.py", line 53, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch)
  File "django/db/models/sql/compiler.py", line 899, in execute_sql
    raise original_exception
  File "django/db/models/sql/compiler.py", line 889, in execute_sql
    cursor.execute(sql, params)
  File "django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)

Sentry: https://sentry.io/organizations/personal-c6b/issues/2351272823/?environment=live&project=1488839&referrer=alert_email

Data Error

DoesNotExist: Book matching query does not exist.
  File "django/db/models/query.py", line 464, in get_or_create
    return self.get(**lookup), False
  File "django/db/models/query.py", line 380, in get
    self.model._meta.object_name

DataError: value too long for type character varying(500)

  File "django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)

DataError: value too long for type character varying(500)

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...
  File "django/db/models/sql/compiler.py", line 1112, in execute_sql
    cursor.execute(sql, params)
  File "django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)

Sentry: Not accessible anymore (because it's too old I think)

I didn't look into them in detail, but it could be that the whole import failed, or only the import of one book/clipping.

[mammuth]

Another occurrence of this error

ValueError: A string literal cannot contain NUL (0x00) characters.
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...
  File "django/db/models/base.py", line 963, in _do_insert
    using=using, raw=raw)
  File "django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "django/db/models/query.py", line 1079, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "django/db/models/sql/compiler.py", line 1112, in execute_sql
    cursor.execute(sql, params)
  File "django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)