add type checking for node notifications

api/institutions/utils.py

@@ -1,7 +1,8 @@
+from website import mails
 from rest_framework import exceptions
 
 from api.base.serializers import relationship_diff
-from osf.models import Institution
+from osf.models import Institution, Node
 from osf.utils import permissions as osf_permissions
 
 
@@ -38,8 +39,7 @@ def update_institutions(resource, new_institutions, user, post=False, notify=Tru
             raise exceptions.PermissionDenied(detail=f'User needs to be affiliated with {inst.name}')
         resource.add_affiliated_institution(inst, user)
 
-    if notify:
-        from website import mails
+    if notify and isinstance(resource, Node):
 
         for user in resource.get_admin_contributors_recursive(unique_users=True):
             mails.send_mail(