fix: catch race conditions when creating users

backend/apps/accounts/views.py

@@ -1,4 +1,5 @@
 from django.contrib.auth import get_user_model
+from django.db import IntegrityError
 from rest_framework import generics, permissions, status
 from rest_framework.response import Response
 from django.utils.translation import gettext as _
@@ -125,13 +126,24 @@ class PhoneAuthRequestView(APIView):
                     {"detail": _("Email already in use.")},
                     status=status.HTTP_400_BAD_REQUEST,
                 )
-            user = User.objects.create_user(
-                email=email,
-                phone_number=phone_number,
-                first_name=data.get("first_name", ""),
-                last_name=data.get("last_name", ""),
-                role="customer",
-            )
+            try:
+                user = User.objects.create_user(
+                    email=email,
+                    phone_number=phone_number,
+                    first_name=data.get("first_name", ""),
+                    last_name=data.get("last_name", ""),
+                    role="customer",
+                )
+            except IntegrityError:
+                user = User.objects.filter(phone_number=phone_number).first()
+                if not user:
+                    # Another worker may have claimed this phone or email after our initial checks.
+                    if email and User.objects.filter(email=email).exists():
+                        return Response(
+                            {"detail": _("Email already in use.")},
+                            status=status.HTTP_400_BAD_REQUEST,
+                        )
+                    raise
 
         try:
             result = create_and_send_otp(