[Findit] Check for availability of try-job result.

appengine/findit/findit_api.py

Index: appengine/findit/findit_api.py
diff --git a/appengine/findit/findit_api.py b/appengine/findit/findit_api.py
index 6b665ec339a192a54ab91c316f01358476ca2894..6e25276a7d4756c75941a339dc292dd070e2614d 100644
--- a/appengine/findit/findit_api.py
+++ b/appengine/findit/findit_api.py
@@ -136,8 +136,13 @@ class FindItApi(remote.Service):
       return None
 
     if build_failure_type == failure_type.COMPILE:
+      if not try_job.compile_results:  # pragma: no cover.
+        return None
       return try_job.compile_results[-1].get('culprit', {}).get(step_name)
 
+    if not try_job.test_results:  # pragma: no cover.
+      return None
+
     if test_name is None:
       step_info = try_job.test_results[-1].get('culprit', {}).get(step_name)
       if not step_info or step_info.get('tests'):  # pragma: no cover.