api: Misc artifacts cleanup.

Dropped low value Args: sections. Added missing type hints.
Added missing return types. Fixed warning vs die convention
for one function.

BUG=None
TEST=run_tests

Change-Id: I268544be6b0beba892f4c8f5c11b578b333cb19c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4009362
Tested-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Alex Klein <saklein@chromium.org>
Auto-Submit: Alex Klein <saklein@chromium.org>
Reviewed-by: Sergey Frolov <sfrolov@google.com>
Commit-Queue: Sergey Frolov <sfrolov@google.com>
diff --git a/api/controller/artifacts_unittest.py b/api/controller/artifacts_unittest.py
index de4f19c..fb651d2 100644
--- a/api/controller/artifacts_unittest.py
+++ b/api/controller/artifacts_unittest.py
@@ -787,10 +787,10 @@
             sysroot=self.does_not_exist,
         )
         response = self.response
-        with self.assertRaises(cros_build_lib.DieSystemExit):
-            artifacts.BundleSimpleChromeArtifacts(
-                request, response, self.api_config
-            )
+        artifacts.BundleSimpleChromeArtifacts(
+            request, response, self.api_config
+        )
+        self.assertFalse(self.response.artifacts)
 
     def testNoOutputDir(self):
         """Test no output dir fails."""