What does this error message mean?
Create Toolchain
I got the same error, and I also have a similar message with the build package version (I use an other version than Leo).
I guess the error message is occuring because we are not running on the latest version of the Node.js build package.
This is Bluemix UI issues, as a workaround, you can try to use a different UI. For example, currently you are using Bluemix Classic UI, you can change to use Bluemix new UI, it will workaround this issue.