How to begin an error/die string? Upper- or lower-case letter?

[Lars Schneider]

Hi,

error() and die() messages seems to begin with upper-case and 
lower-case letters in the Git code base:

  git grep 'error(_' | perl -nE 'say /.*error\(_\("(.).*/' | sort | uniq -c
  git grep 'die(_' | perl -nE 'say /.*die\(_\("(.).*/' | sort | uniq -c

Do we prefer one way over the other?

Thanks,
Lars