anchor.diff:    io_lib:format(Fmt, Args);
   
   %% Rewrite nomatch_guard to be more generic it can happen inside if, unless, etc.
  -format_error(sys_core_fold, nomatch_guard) ->
  +custom_format(sys_core_fold, nomatch_guard) ->
     "this check/guard will always yield the same result";
   
   %% Handle literal eval failures
  -format_error(sys_core_fold, {eval_failure, Error}) ->
  +custom_format(sys_core_fold, {eval_failure, Error}) ->
     #{'__struct__' := Struct} = 'Elixir.Exception':normalize(error, Error),
     ["this expression will fail with ", elixir_aliases:inspect(Struct)];
   
  -format_error([], Desc) ->
  +custom_format([], Desc) ->
     io_lib:format("~p", [Desc]);
   
  -format_error(Module, Desc) ->
  +custom_format(Module, Desc) ->
     Module:format_error(Desc).
  +
  +%% Error formatting
  +
  +format_error({invalid_compilation, Module}) ->
  +  io_lib:format(
  +    "could not compile module ~ts. We expected the compiler to return a .beam binary but "
  +    "got something else. This usually happens because ERL_COMPILER_OPTIONS or @compile "
  +    "was set to change the compilation outcome in a way that is incompatible with Elixir",
  +    [elixir_aliases:inspect(Module)]
  +  ).
  
positive.code: handle_file_error(File, {beam_validator, Rest}) ->
    elixir_errors:form_error([{line, 0}], File, beam_validator, Rest);
  handle_file_error(File, {Line, Module, Desc}) ->
    Message = format_error(Module, Desc),
    elixir_errors:compile_error([{line, Line}], File, Message).
  
  %% Custom formatting
  
  %% Mention the capture operator in make_fun
  format_error(sys_core_fold, {no_effect, {erlang, make_fun, 3}}) ->
    "the result of the capture operator & (:erlang.make_fun/3) is never used";
  
  %% Make no_effect clauses pretty
  format_error(sys_core_fold, {no_effect, {erlang, F, A}}) ->
    {Fmt, Args} = case erl_internal:comp_op(F, A) of
      true -> {"use of operator ~ts has no effect", [elixir_utils:erlang_comparison_op_to_elixir(F)]};
      false ->
  
negative.code: -module(elixir_erl_compiler).
  -export([spawn/2, forms/3, noenv_forms/3, erl_to_core/2, format_error/1]).
  -include("elixir.hrl").
  
  spawn(Fun, Args) ->
  