title: (admin.E108) The value of 'list_display[1]' refers to 'label', which is not a callable, an attribute of '?', or an attribute or method on 'org.Org'
body: <p>I get the error : (admin.E108) The value of 'list_display[1]' refers to 'label', which is not a callable, an attribute of 'OrgAdmin', or an attribute or method on 'org.Org'. when I try to remove the field label, I don't understand why. (sqlite3)</p>
  
  <p>It feels like django has referenced that field somewhere (I was using it in the <strong>str</strong> function before refactoring and I don't know how to sync it up or something.</p>
  
  <pre><code>from django.db import models
  
  
  class Org(models.Model):
    class Meta:
      # https://docs.djangoproject.com/en/2.1/ref/models/options/#django.db.models.Options.db_table
      db_table = "tfp_backoffice_org"
      verbose_name = 'Organization'
  
      # https://docs.djangoproject.com/en/2.1/ref/models/options/#indexes
      indexes = [
        models.Index(fields=['name', 'name']),
      ]
  
    name = models.CharField(
      help_text="Optional (autogenerated).&lt;br /&gt;"
                "Must be url-compliant (slug, using '-' dash separator, no space, special char, etc.)",
      max_length=100,
    )
    label = models.CharField(
      help_text="Label displayed in French language",
      max_length=100,
    )
    label_fr = models.CharField(
      help_text="Label displayed in French language",
      max_length=100,
      blank=True,
      default="",
    )
    label_en = models.CharField(
      help_text="Label displayed in English language",
      max_length=100,
      blank=True,
      default="",
    )
  
    def __str__(self):
      return self.label_fr
  </code></pre>