Fix Github Trigger handling when there is no committer

endpoints/trigger.py

@@ -318,21 +318,27 @@ class GithubBuildTrigger(BuildTrigger):
       logger.exception('Could not load data for commit')
       return
 
-    return {
+    commit_info = {
       'url': commit.html_url,
       'message': commit.commit.message,
-      'author': {
+      'date': commit.last_modified
+    }
+
+    if commit.author:
+      commit_info['author'] = {
         'username': commit.author.login,
         'avatar_url': commit.author.avatar_url,
         'url': commit.author.html_url
-      },
-      'committer': {
+      }
+
+    if commit.committer:
+      commit_info['committer'] = {
         'username': commit.committer.login,
         'avatar_url': commit.committer.avatar_url,
         'url': commit.committer.html_url
-      },
-      'date': commit.last_modified
-    }
+      }
+
+    return commit_info
 
   @staticmethod
   def _prepare_build(config, repo, commit_sha, build_name, ref):