Fuzzy Select: Buffer is not always empty at the end of render

[deg0nz]

I found this bug while implementing #179.

As you can see in the gif in the PR, at some point the end of the prompt prints the characters for the arrow down keyboard. But this also happens with normal characters entered to the prompt.

Here's a screenshot:

Unfortunately, I was not able to spot the source of the error. Maybe someone could help here. I would like to implement a fix if someone could point me in the right direction.

The error is not directly reproducible. I tried many character combinations but it seems to only happen when I quickly enter characters, so this could be a timing issue somewhere.