Do not erase elixir_compiler_pid

Author: José Valim

lib/elixir/lib/kernel/error_handler.ex

@@ -25,10 +25,10 @@ defmodule Kernel.ErrorHandler do
           { ^ref, :ready } ->
             :ok
           { ^ref, :release } ->
-            # On release, get rid of the compiler pid,
-            # no further allow elixir_ensure_compiled directives
-            # and revert to the original error handler.
-            :erlang.erase(:elixir_compiler_pid)
+            # On release, no further allow elixir_ensure_compiled
+            # directives and revert to the original error handler.
+            # Note we should not delete the elixir_compiler_pid though,
+            # as we still want to send notifications to the compiler.
             :erlang.erase(:elixir_ensure_compiled)
             :erlang.process_flag(:error_handler, :error_handler)
         end