artifacts: BundleChromeOSConfig no error on missing config

Do not error when the artifact cannot be generated in
BundleChromeOSConfig. The artifact is expected to be missing
if the builder errors before the sysroot is built.

BUG=b:209652987
TEST=./run_tests

Change-Id: I7e4267c7dc9eb72eeb395ebe875e63f263a49749
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3321673
Tested-by: Alex Klein <saklein@chromium.org>
Auto-Submit: Alex Klein <saklein@chromium.org>
Reviewed-by: Lizzy Presland <zland@google.com>
Commit-Queue: Alex Klein <saklein@chromium.org>
diff --git a/api/controller/artifacts_unittest.py b/api/controller/artifacts_unittest.py
index 71ce347..f80fd38 100644
--- a/api/controller/artifacts_unittest.py
+++ b/api/controller/artifacts_unittest.py
@@ -538,12 +538,12 @@
                      [mock.call(mock.ANY, self.sysroot, self.output_dir)])
 
   def testBundleChromeOSConfigNoConfigFound(self):
-    """An error is raised if the config payload isn't found."""
+    """Empty results when the config payload isn't found."""
     self.PatchObject(artifacts_svc, 'BundleChromeOSConfig', return_value=None)
 
-    with self.assertRaises(cros_build_lib.DieSystemExit):
-      artifacts.BundleChromeOSConfig(self.sysroot_request, self.response,
-                                     self.api_config)
+    artifacts.BundleChromeOSConfig(self.sysroot_request, self.response,
+                                   self.api_config)
+    self.assertFalse(self.response.artifacts)
 
 
 class BundleTestUpdatePayloadsTest(cros_test_lib.MockTempDirTestCase,