Disregarding a Tell block if application doesn't exist on the system

I would like for this script to ignore and not show the “Choose Application” dialog if the GrowlHelperApp is not found on the system.

Here is the code that I am using:

set GrowlIsRunning to check_Application_exists("com.Growl.GrowlHelperApp")

on check_Application_exists(theApp)
		tell application "Finder" to application file id theApp
		return true
	on error
		return false
	end try
end check_Application_exists

if GrowlIsRunning is true then
	tell application "GrowlHelperApp"
		return "it exists"
	end tell
	return "no good"
end if

I run into the Choose Application window. When I run it and when I try to compile the code. Please advise. Thank you!



the problem is, every application, which is specified with a literal string, must exist at compile time.
If you compile the script on a machine with Growl installed and run the script later on a machine without Growl, it will work

Ok, I understand. Thank you for the speedy response.