If playing offline with migrated Minecraft account commands only accept your email address, not player name.

If you are offline with a migrated Minecraft account and you use a command and you type in your player name the screen will say "that player cannot be found" but if you type in you email address it will accept it.

What I expected to happen was:
I could type in my player name and the command would work normally

What actually happened was:
I tried to type in my player name but the command did not work in order to get it to work was I had to type on my email address

Steps to reproduce:
1. Have a Migrated minecraft account
2. play minecraft offline
3. type your player name in a command