SSO bug fix (#4972)

* Catch SSO error

- If social application is not assigned to at least one site, errors happen
- Check if at least one site is enabled

* Docs updates

* Typo fix

InvenTree/part/templatetags/sso.py

@@ -1,5 +1,6 @@
 """This module provides template tags pertaining to SSO functionality"""
 
+import logging
 
 from django import template
 
@@ -7,6 +8,7 @@ from common.models import InvenTreeSetting
 from InvenTree.helpers import str2bool
 
 register = template.Library()
+logger = logging.getLogger('inventree')
 
 
 @register.simple_tag()
@@ -32,13 +34,23 @@ def sso_auto_enabled():
 def sso_check_provider(provider):
     """Return True if the given provider is correctly configured"""
 
+    import allauth.app_settings
     from allauth.socialaccount.models import SocialApp
 
     # First, check that the provider is enabled
-    if not SocialApp.objects.filter(provider__iexact=provider.name).exists():
+    apps = SocialApp.objects.filter(provider__iexact=provider.name)
+
+    if not apps.exists():
         return False
 
     # Next, check that the provider is correctly configured
+    app = apps.first()
+
+    if allauth.app_settings.SITES_ENABLED:
+        # At least one matching site must be specified
+        if not app.sites.exists():
+            logger.error(f"SocialApp {app} has no sites configured")
+            return False
 
     # At this point, we assume that the provider is correctly configured
     return True