Dan,

  Is that error not triggering an error rule? if it does, you can find the error code and do a match on that code in eror rule. You can either use the error-message in service context or use your own customized error messages.

 If it is not triggering, then probably you might have to go with a on-error action. In that you can define the rule that need to be called.

 Also, there is a list of error codes under Administration->Debug->View List of Event Codes.

Hope this helps,
Sudhish