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NAME

       error_handler - Default system error handler.

DESCRIPTION

       This module defines what happens when certain types of errors occur.

EXPORTS

       raise_undef_exception(Module, Function, Args) -> no_return()

              Types:

                 Module = Function = atom()
                 Args = list()
                    A (possibly empty) list of arguments Arg1,..,ArgN

              Raises  an  undef exception with a stacktrace, indicating that Module:Function/N is
              undefined.

       undefined_function(Module, Function, Args) -> any()

              Types:

                 Module = Function = atom()
                 Args = list()
                    A (possibly empty) list of arguments Arg1,..,ArgN

              This  function  is  called  by  the  runtime  system  if  a   call   is   made   to
              Module:Function(Arg1,.., ArgN) and Module:Function/N is undefined. Notice that this
              function is evaluated inside the process making the original call.

              This function first attempts to autoload Module. If that is not possible, an  undef
              exception is raised.

              If it is possible to load Module and function Function/N is exported, it is called.

              Otherwise,  if function '$handle_undefined_function'/2 is exported, it is called as
              '$handle_undefined_function'(Function, Args).

          Warning:
              Defining '$handle_undefined_function'/2 in  ordinary  application  code  is  highly
              discouraged.  It  is  very  easy to make subtle errors that can take a long time to
              debug. Furthermore, none of the tools for static code analysis  (such  as  Dialyzer
              and  Xref)  supports  the use of '$handle_undefined_function'/2 and no such support
              will be added. Only use this function after having carefully considered other, less
              dangerous, solutions. One example of potential legitimate use is creating stubs for
              other sub-systems during testing and debugging.

              Otherwise an undef exception is raised.

       undefined_lambda(Module, Fun, Args) -> term()

              Types:

                 Module = atom()
                 Fun = function()
                 Args = list()
                    A (possibly empty) list of arguments Arg1,..,ArgN

              This function is evaluated if a call is made to Fun(Arg1,.., ArgN) when the  module
              defining the fun is not loaded. The function is evaluated inside the process making
              the original call.

              If Module is interpreted, the interpreter is invoked and the return  value  of  the
              interpreted Fun(Arg1,.., ArgN) call is returned.

              Otherwise,  it returns, if possible, the value of apply(Fun, Args) after an attempt
              is made to autoload Module. If this is not  possible,  the  call  fails  with  exit
              reason undef.

NOTES

       The  code  in  error_handler  is complex. Do not change it without fully understanding the
       interaction between the error handler, the init process of the code server,  and  the  I/O
       mechanism of the code.

       Code  changes  that seem small can cause a deadlock, as unforeseen consequences can occur.
       The use of input is dangerous in this type of code.