In this blog entry “Why JWSCL mainly uses exceptions instead of returned error values” I told you why JWSCL uses mainly exceptions instead of return values. However this design also have problems. A bad programmer may simply swallow the exception like this:

try
  JwEnablePrivilege();
except
  //do nothing
end;

//do sth here that needs the privilege enabled.

If you or someone you know tend to such a behavior you should read Patrick Joyce’s article “How to abuse exceptions”. Also do not forget to read the pdf about “Toward Exception Handling Best Practices and Patterns” which is mentioned in the first sentence.