Guess I'll be the first to say that the "twist" was not appropriate. The question was titled and about the TRY...CATCH structure in SQL Server, the string length was a "Gotcha!" in an ISNULL statement.
Who cares about points though?
I would not use your presumed approach to maintain code in the wild.
The comments at the top of a code-block may say what the code is "supposed" to do. But that does not mean I can go blindly into the code thinking that in fact is what the code is doing. I still have the responsibility to understand every line from top to bottom not just one particular section or another.
It's definitely a tricky question but at least all the information needed is provided. Congratulations to the author!