Launcher gives wrong message when you sign in with username instead of email.

I have a migrated Minecraft account and I accidentally put my username instead of my email in the username box.

What I expected to happen was for the launcher to tell me I need to use my email because my account was migrated, like in the old launcher.

What actually happened was that it told me my password/username was incorrect. This could be an issue for people who don't remember they're supposed to put their email.

Steps to Reproduce:
1. Migrate Minecraft account
2. Open launcher
3. Log in to the game with username instead of email