Right now we just log an error and fall-back on the old action. However that doesn't make any sense because:
1) There's no old action associated with this URL type (that's why a ResourceReferenceHandler was used in the first place), and thus it falls back on ViewAction which is not going to do what was expected for sure.
2) We don't know the state of the servlet output response at this stage and more generally the state of XWiki and we cannot assume all is fine.
Thus the only valid option is to throw an exception.