chore(ruff): Enable RET rules and add explicit fallbacks

Adopt Ruff `RET` to improve return-flow consistency across the codebase.
Simplify control flow by removing redundant `else` blocks after
`return`, and add explicit `return None` (or equivalent) fallbacks
where appropriate to preserve existing behavior.

Fixes #21411

netbox/core/models/data.py

@@ -98,6 +98,7 @@ class DataSource(JobsMixin, PrimaryModel):
     def get_type_display(self):
         if backend := registry['data_backends'].get(self.type):
             return backend.label
+        return None
 
     def get_status_color(self):
         return DataSourceStatusChoices.colors.get(self.status)

netbox/core/models/files.py

@@ -79,8 +79,7 @@ class ManagedFile(SyncedDataMixin, models.Model):
                 'scripts': settings.SCRIPTS_ROOT,
                 'reports': settings.REPORTS_ROOT,
             }[self.file_root]
-        else:
-            return ""
+        return ""
 
     def sync_data(self):
         if self.data_file:

netbox/core/models/jobs.py

@@ -146,7 +146,7 @@ class Job(models.Model):
         if self.object_type:
             if self.object_type.model == 'reportmodule':
                 return reverse('extras:report_result', kwargs={'job_pk': self.pk})
-            elif self.object_type.model == 'scriptmodule':
+            if self.object_type.model == 'scriptmodule':
                 return reverse('extras:script_result', kwargs={'job_pk': self.pk})
         return reverse('core:job', args=[self.pk])
 

netbox/core/models/object_types.py

@@ -218,19 +218,22 @@ class ObjectType(ContentType):
     def app_verbose_name(self):
         if model := self.model_class():
             return model._meta.app_config.verbose_name
+        return None
 
     @property
     def model_verbose_name(self):
         if model := self.model_class():
             return model._meta.verbose_name
+        return None
 
     @property
     def model_verbose_name_plural(self):
         if model := self.model_class():
             return model._meta.verbose_name_plural
+        return None
 
     @property
     def is_plugin_model(self):
         if not (model := self.model_class()):
-            return  # Return null if model class is invalid
+            return None  # Return null if model class is invalid
         return isinstance(model._meta.app_config, PluginConfig)