Display an error message if a php script breaks -

As the question suggests, I would like to display an error message when a php script is broken. Suppose

  $ var = some functions ();   
 If a task has a code that breaks the script, then I want to return a custom message.  
  As is ($ var  true) // Here is a error message   
 Here is a timeout function which is used for maximum time execution Can detect and display error message?   
 
 
 You need to use  set_error_handler  and I think you    Trigger_error ();