Fix a hard-crash when querying custom code endpoint with invalid builder ID. (baserow#4964)

Author: paljort

changelog/entries/unreleased/bug/fixed_a_crash_when_querying_custom_code_endpoint_with_an_inv.json

@@ -0,0 +1,9 @@
+{
+    "type": "bug",
+    "message": "Fixed a crash when fetching custom code for a non-existent builder ID.",
+    "issue_origin": "github",
+    "issue_number": null,
+    "domain": "builder",
+    "bullet_points": [],
+    "created_at": "2026-03-12"
+}

enterprise/backend/src/baserow_enterprise/api/builder/custom_code/views.py

@@ -5,11 +5,11 @@
 from rest_framework.permissions import AllowAny
 from rest_framework.views import APIView
 
+from baserow.api.applications.errors import ERROR_APPLICATION_DOES_NOT_EXIST
 from baserow.api.decorators import map_exceptions
 from baserow.api.schemas import get_error_schema
-from baserow.contrib.builder.errors import ERROR_BUILDER_DOES_NOT_EXIST
-from baserow.contrib.builder.exceptions import BuilderDoesNotExist
 from baserow.contrib.builder.service import BuilderService
+from baserow.core.exceptions import ApplicationDoesNotExist
 from baserow_enterprise.api.authentication import (
     AuthenticateFromUserSessionAuthentication,
 )
@@ -46,12 +46,16 @@ class PublicCustomCodeView(APIView):
         description=("Returns the css/js for the given builder."),
         responses={
             200: str,
-            404: get_error_schema(["ERROR_BUILDER_DOES_NOT_EXIST"]),
+            404: get_error_schema(
+                [
+                    "ERROR_APPLICATION_DOES_NOT_EXIST",
+                ]
+            ),
         },
     )
     @map_exceptions(
         {
-            BuilderDoesNotExist: ERROR_BUILDER_DOES_NOT_EXIST,
+            ApplicationDoesNotExist: ERROR_APPLICATION_DOES_NOT_EXIST,
         }
     )
     def get(self, request, builder_id, code_type):

enterprise/backend/tests/baserow_enterprise_tests/builder/custom_code/test_enterprise_application_views.py

@@ -263,3 +263,17 @@ def test_get_enterprise_builder_custom_code_public_no_licence(api_client, data_f
         url,
     )
     assert response.status_code == HTTP_404_NOT_FOUND
+
+
+@pytest.mark.django_db
+def test_get_enterprise_builder_custom_code_public_application_not_found(
+    enable_enterprise, api_client, data_fixture
+):
+    url = reverse(
+        "api:enterprise:custom_code:public_js",
+        kwargs={"builder_id": 123456},
+    )
+
+    response = api_client.get(url)
+
+    assert response.status_code == HTTP_404_NOT_FOUND