What does it mean to call a function safely? I have a desktop application with a single exception handler wrapping it's event loop. The handler display the me

What does it mean to call a function safely? I have a desktop application with a single exception handler wrapping it's event loop. The handler display the message to the user and returns the to loop. It's rock solid -- nothing can crash it. The user can try to save their file to some network share that just disappeared and when that fails just save again somewhere else. But there is no such thing a safe function to call. Whether you handle errors by meticulously passing them around everywhere or not makes little difference.