add missing import

invokeai/app/services/download/download_default.py

@@ -270,7 +270,7 @@ class DownloadQueueService(DownloadQueueServiceBase):
             job.dest.parent.mkdir(parents=True, exist_ok=True)
             job.download_path = job.dest
 
-        assert job.download_path
+        assert job.download_path is not None
 
         # Don't clobber an existing file. See commit 82c2c85202f88c6d24ff84710f297cfc6ae174af
         # for code that instead resumes an interrupted download.
@@ -280,6 +280,9 @@ class DownloadQueueService(DownloadQueueServiceBase):
         # append ".downloading" to the path
         in_progress_path = self._in_progress_path(job.download_path)
 
+        # catch rare race condition that is appearing in unit tests.
+        assert in_progress_path.parent.exists(), f"Directory doesn't exist! in_progress_path={in_progress_path}; parent={in_progress_path.parent}"
+
         # signal caller that the download is starting. At this point, key fields such as
         # download_path and total_bytes will be populated. We call it here because the might
         # discover that the local file is already complete and generate a COMPLETED status.

tests/app/services/model_install/test_model_install.py

@@ -3,6 +3,7 @@ Test the model installer
 """
 
 import platform
+import time
 import uuid
 from pathlib import Path
 from typing import Any, Dict
@@ -255,6 +256,10 @@ def test_huggingface_download(mm2_installer: ModelInstallServiceBase, mm2_app_co
     assert isinstance(bus, EventServiceBase)
     assert store is not None
 
+    # test hypothesis that there is a race condition between
+    # creating temporary directory and downloading into it.
+    time.sleep(2)  
+    
     job = mm2_installer.import_model(source)
     job_list = mm2_installer.wait_for_installs(timeout=10)
     assert len(job_list) == 1