Since the last result is not set for results that are either null or false, the result is also not printed to the console.
This is highly confusing if you have a command that returns a boolean value. if the return value is true, it will be shown at set as last result, if it is false it looks like it gets ignored.
I don't think this is the correct behavior. I understand the null case, but false should clearly be a valid return value for a command.