The error tag has gotten to the point where mods should probably ask SE employees to blacklist it.
That's how tag blacklisting is achieved.
This tag seems to come back slowly--a couple posts here and there. But I can't deny it keeps coming back. Furthermore, it doesn't seem like discussion of it on meta has kept it from returning. It might even be coming back more often than in the past (though if so, I suspect that's just because we're policing it better now--the more times we get rid of it, the more times it's possible for it to come back).
I've been skeptical of blacklisting this, partly for reasons jrg articulates here and in this comment (where he says, "tags are only blacklisted if it's really, really, really big and evil. I can't reveal the full details, but there are only 4 blacklists, and half of them are spam site related.")
However, as this keeps coming back, and shows no sign that it will stop coming back, it seems that the applicable standard is to blacklist it. Unless things have changed since August 2011, the guideline in this post by Jeff Atwood probably still applies:
Ok this tag is now blacklisted; any tag we destroy that comes back from the dead, needs to be blacklisted.
So, I recommend an AU moderator at least talk to Stack Exchange about this. (Unless there is a newer, higher bar for blacklisting that I'm not aware of.)