csc: handle CSC returning errors
csc: handle CSC returning errors

CSC doesn't actually return errors in some situations (see
https://github.com/fusiyuan2010/CSC/issues/10) which is why the plugin
remains disabled, but with this we handle them so when CSC is fixed
we will be ready.

quixdb/squash,quixdb/squash,jibsen/squash,jibsen/squash,jibsen/squash,quixdb/squash,Cloudef/squash,Cloudef/squash,Cloudef/squash