graph/errocode: Rework FromCS3Status

The handling of 'error' has been moved from FromStat() to FromCS3Status().
It's generally useful for other users of FromCS3Status()
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f