Why should interactive search results raise errors?

[Lennart Borgman]

Some interactive search functions raise errors when no hit is found. It 
is quite annoyning if you have set debug-on-error to t. Is there any 
reason why this functions raises errors in this cases? Can that be used 
for anything?

An example is the function in the menu bar: Edit - Search - String 
Forward. As far as I can see this in only meant to be run interactively. 
The same goes for viper-search-next.

It would in my opinion be more convenient if these functions just return 
nil and showed a message when a search fails. Would it not be a good 
convention for interactive search functions in Emacs?