Error message with bad citation/reference

[Bob Alvarez]

Is there a way to get Lyx to display an error message when it cannot 
find a citation in a bibtex database or a cross-reference to a label in 
the document?

So far, it just silently puts a question mark or some other indication 
in the pdf but this is an important error that I need to correct. In 
small documents these are easy to spot but in large documents like a 
book with multiple child files these can be easy to miss.

TIA

Bob