Do not crash IEx on :init.stop

Author: José Valim

lib/elixir/lib/macro.ex

@@ -131,7 +131,7 @@ defmodule Macro do
       valid_alias?(charlist) ->
         :alias
       true ->
-        case :elixir_config.get(:identifier_tokenizer).tokenize(charlist) do
+        case :elixir_config.safe_get(:identifier_tokenizer, String.Tokenizer).tokenize(charlist) do
           {kind, _acc, [], _, _, special} ->
             if kind == :identifier and not :lists.member(?@, special) do
               :callable

lib/elixir/lib/uri.ex

@@ -42,7 +42,7 @@ defmodule URI do
   """
   @spec default_port(binary) :: nil | non_neg_integer
   def default_port(scheme) when is_binary(scheme) do
-    :elixir_config.get({:uri, scheme})
+    :elixir_config.safe_get({:uri, scheme}, nil)
   end
 
   @doc """

lib/elixir/src/elixir_config.erl

@@ -1,6 +1,6 @@
 -module(elixir_config).
 -compile({no_auto_import, [get/1]}).
--export([new/1, delete/1, put/2, get/1, update/2, get_and_put/2]).
+-export([new/1, delete/1, put/2, get/1, safe_get/2, update/2, get_and_put/2]).
 -export([start_link/0, init/1, handle_call/3, handle_cast/2,
   handle_info/2, code_change/3, terminate/2]).
 -behaviour(gen_server).
@@ -19,9 +19,15 @@ put(Key, Value) ->
   gen_server:call(?MODULE, {put, Key, Value}).
 
 get(Key) ->
-  case ets:lookup(?MODULE, Key) of
+  [{_, Value}] = ets:lookup(?MODULE, Key),
+  Value.
+
+safe_get(Key, Default) ->
+  try ets:lookup(?MODULE, Key) of
     [{_, Value}] -> Value;
-    []          -> nil
+    [] -> Default
+  catch
+    _:_ -> Default
   end.
 
 update(Key, Fun) ->

lib/elixir/src/elixir_tokenizer.erl

@@ -142,7 +142,7 @@ tokenize(String, Line, Column, Opts) ->
     existing_atoms_only=ExistingAtomsOnly,
     check_terminators=CheckTerminators,
     preserve_comments=PreserveComments,
-    identifier_tokenizer=elixir_config:get(identifier_tokenizer)
+    identifier_tokenizer=elixir_config:safe_get(identifier_tokenizer, 'Elixir.String.Tokenizer')
   }).
 
 tokenize(String, Line, Opts) ->

lib/elixir/src/elixir_utils.erl

@@ -96,21 +96,17 @@ relative_to_cwd(Path) ->
 characters_to_list(Data) when is_list(Data) ->
   Data;
 characters_to_list(Data) ->
-  try elixir_config:get(bootstrap) of
+  case elixir_config:safe_get(bootstrap, true) of
     true  -> unicode:characters_to_list(Data);
     false -> 'Elixir.String':to_charlist(Data)
-  catch
-    _:_ -> unicode:characters_to_list(Data)
   end.
 
 characters_to_binary(Data) when is_binary(Data) ->
   Data;
 characters_to_binary(Data) ->
-  try elixir_config:get(bootstrap) of
-    true  -> unicode:characters_to_binary(Data);
+  case elixir_config:safe_get(bootstrap, true) of
+    true -> unicode:characters_to_binary(Data);
     false -> 'Elixir.List':to_string(Data)
-  catch
-    _:_ -> unicode:characters_to_binary(Data)
   end.
 
 %% Returns the caller as a stacktrace entry.