u/Asteroiderer

I want to change my username/handle on GitHub to @ Asteroider, but the settings dialog for it says that name is unavailable. However, when I go to https://github.com/Asteroider/ it gives me a 404, whereas other options like @ Asteroid and @ Asteroiderer do have accounts that I can view.
Is there any way to fix this, since GitHub support is apparently like YouTube's in that they are so high and mighty they only support people who can pay or make money on their platforms?

I've tried all the humming apps and such, and I've tried advanced specific searches. I can't seem to find anything on this.
It's a 21st century pop song that I'm sure was played on general-audience radio stations all the time a decade ago. I'm sure there's a female singer, and the only line I can somewhat remember is something like "whenever I look out my window".
Here's the speakpipe recording of me trying to replicate what its memory sounds like in my head: https://www.speakpipe.com/voice-recorder/msg/y7o7nihw9n6otr8b

From that, I hope you can tell it has a kind of somber tone to it. It's just an earworm lately and I really don't think I've heard it in many years.

Thank you so much, in advance, for trying to help me.