Its structure,error handling,error recovery and repair techniques.
The tasks of the Error Handling process are to detect each error, report it to the user, and then make some recover strategy and implement them to handle error. During this whole process processing time of program should not be slow. An Error is the blank entries in the symbol table.
Error Recovery :The basic requirement for the compiler is to simply stop and issue a message, and cease compilation. There are some common recovery methods that are follows : Panic mode recovery, Phase level recovery, Error productions,Global correction