Tooltip for today's "Error wildcard" checkbox:
If option enabled then mapping with code pattern '*' only applies to URLs having bad HTTP status (0, 4*, 5*).
Otherwise '*' applies to any HTTP status.
The problem with this setting is that there are many other statuses an URL can get, which are not covered here. For instance any case where the webserver cannot give a resonse code, "URL_TIMEOUT" etc.
It would be to prefer that the function of this checkbox is inverted, so that instead of saying what statuses are bad, you state which ones are good (2*, 3*), and make all the others bad. Then it would be possible to use severity mapping even if there is no status code.
This is a good idea, we need to review it further to see what we need to to in order to implement it in the best possible way. After that we will plan it into a release. We will come back to you with a more detailed release plan.