On this page:
drracket:  init:  original-error-display-handler

26 drracket:init

procedure

(drracket:init:original-error-display-handler message    
  exn)  any
  message : string?
  exn : any/c
This is the error-display-handler installed at the time that DrRacket starts up.

DrRacket sets the error-display-handler to one that shows an “Internal Error” dialog box.