It seems the string candidates produced by consult-buffer have some
extra non-printable bytes appended at the end. These bytes makes flx-rs
not match against the candidate properly.
Consult does add a text property to the candidate string called 'buffer,
which contains the original buffer name.
So for now, we advice the flx-rs-score function and attempt to the
extract the buffer text property from the input candidate and use that
instead. If the candidate has no such text property, we use it as is.