fix: DEV-4039: Download storage empty path (HumanSignal#3448)

Author: triklozoid

label_studio/data_import/api.py

@@ -487,6 +487,10 @@ def get(self, request, *args, **kwargs):
         """ Get export files list
         """
         request = self.request
+        filepath = request.GET.get('filepath')
+        if filepath is None:
+            return Response(status=status.HTTP_404_NOT_FOUND)
+
         filepath = unquote(request.GET['filepath'])
 
         url = None

label_studio/tests/test_download_storage.tavern.yml

@@ -0,0 +1,27 @@
+---
+test_name: tasks_download_storage
+strict: false
+marks:
+- usefixtures:
+  - django_live_url
+stages:
+- name: without auth
+  request:
+    method: GET
+    url: '{django_live_url}/storage-data/uploaded/'
+  response:
+    status_code: 401
+- id: signup
+  type: ref
+- name: empty filepath
+  request:
+    method: GET
+    url: '{django_live_url}/storage-data/uploaded/'
+  response:
+    status_code: 404
+- name: access denied
+  request:
+    method: GET
+    url: '{django_live_url}/storage-data/uploaded/?filepath=test'
+  response:
+    status_code: 403