Fixed #15877 -- Improved exception when ModelForm has no model class

Thanks theaspect at gmail.com for the report and volrath for the
patch.

1 files changed, 2 insertions, 2 deletions

diff --git a/django/forms/models.py b/django/forms/models.py
index d545a07488..75d526d173 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -233,9 +233,9 @@ class BaseModelForm(BaseForm):
                  initial=None, error_class=ErrorList, label_suffix=':',
                  empty_permitted=False, instance=None):
         opts = self._meta
+        if opts.model is None:
+            raise ValueError('ModelForm has no model class specified.')
         if instance is None:
-            if opts.model is None:
-                raise ValueError('ModelForm has no model class specified.')
             # if we didn't get an instance, instantiate a new one
             self.instance = opts.model()
             object_data = {}