Properly rescue from JSON parse.

lib/gitlab_lfs_authentication.rb

@@ -11,8 +11,12 @@ class GitlabLfsAuthentication
   end
 
   def self.build_from_json(json)
-    values = JSON.parse(json) rescue nil
-    self.new(values['username'], values['lfs_token'], values['repository_http_path'])
+    begin
+      values = JSON.parse(json)
+      self.new(values['username'], values['lfs_token'], values['repository_http_path'])
+    rescue
+      nil
+    end
   end
 
   def authentication_payload